Add string extensions quote and reverse

conformance/src/test/java/dev/cel/conformance/BUILD.bazel

@@ -119,8 +119,7 @@ _TESTS_TO_SKIP_LEGACY = [
 
  # Skip until fixed.
  "fields/qualified_identifier_resolution/map_value_repeat_key_heterogeneous",
- # TODO: Add strings.format and strings.quote.
- "string_ext/quote",
+ # TODO: Add strings.format.
  "string_ext/format",
  "string_ext/format_errors",
 
@@ -148,8 +147,7 @@ _TESTS_TO_SKIP_LEGACY = [
 ]
 
 _TESTS_TO_SKIP_PLANNER = [
- # TODO: Add strings.format and strings.quote.
- "string_ext/quote",
+ # TODO: Add strings.format.
  "string_ext/format",
  "string_ext/format_errors",
 

extensions/src/main/java/dev/cel/extensions/CelStringExtensions.java

@@ -137,6 +137,17 @@ public enum Function {
  SimpleType.STRING,
  SimpleType.STRING)),
  CelFunctionBinding.from("string_lower_ascii", String.class, Ascii::toLowerCase)),
+ QUOTE(
+ CelFunctionDecl.newFunctionDeclaration(
+ "strings.quote",
+ CelOverloadDecl.newGlobalOverload(
+ "strings_quote",
+ "Takes the given string and makes it safe to print (without any formatting"
+ + " due to escape sequences). If any invalid UTF-8 characters are"
+ + " encountered, they are replaced with \\uFFFD.",
+ SimpleType.STRING,
+ ImmutableList.of(SimpleType.STRING))),
+ CelFunctionBinding.from("strings_quote", String.class, CelStringExtensions::quote)),
  REPLACE(
  CelFunctionDecl.newFunctionDeclaration(
  "replace",
@@ -164,6 +175,16 @@ public enum Function {
  "string_replace_string_string_int",
  ImmutableList.of(String.class, String.class, String.class, Long.class),
  CelStringExtensions::replace)),
+ REVERSE(
+ CelFunctionDecl.newFunctionDeclaration(
+ "reverse",
+ CelOverloadDecl.newMemberOverload(
+ "string_reverse",
+ "Returns a new string whose characters are the same as the target string,"
+ + " only formatted in reverse order.",
+ SimpleType.STRING,
+ SimpleType.STRING)),
+ CelFunctionBinding.from("string_reverse", String.class, CelStringExtensions::reverse)),
  SPLIT(
  CelFunctionDecl.newFunctionDeclaration(
  "split",
@@ -449,6 +470,67 @@ private static Long lastIndexOf(CelCodePointArray str, CelCodePointArray substr,
  return -1L;
  }
 
+ private static String quote(String s) {
+ StringBuilder sb = new StringBuilder(s.length() + 2);
+ sb.append('"');
+ for (int i = 0; i < s.length(); ) {
+ int codePoint = s.codePointAt(i);
+ if (isMalformedUtf16(s, i, codePoint)) {
+ sb.append('\uFFFD');
+ i++;
+ continue;
+ }
+ switch (codePoint) {
+ case '\u0007':
+ sb.append("\\a");
+ break;
+ case '\b':
+ sb.append("\\b");
+ break;
+ case '\f':
+ sb.append("\\f");
+ break;
+ case '\n':
+ sb.append("\\n");
+ break;
+ case '\r':
+ sb.append("\\r");
+ break;
+ case '\t':
+ sb.append("\\t");
+ break;
+ case '\u000B':
+ sb.append("\\v");
+ break;
+ case '\\':
+ sb.append("\\\\");
+ break;
+ case '"':
+ sb.append("\\\"");
+ break;
+ default:
+ sb.appendCodePoint(codePoint);
+ break;
+ }
+ i += Character.charCount(codePoint);
+ }
+ sb.append('"');
+ return sb.toString();
+ }
+
+ private static boolean isMalformedUtf16(String s, int index, int codePoint) {
+ char currentChar = s.charAt(index);
+ if (!Character.isValidCodePoint(codePoint)) {
+ return true;
+ }
+ if (Character.isLowSurrogate(currentChar)) {
+ return true;
+ }
+ // Check for unpaired high surrogate
+ return Character.isHighSurrogate(currentChar)
+ && (index + 1 >= s.length() || !Character.isLowSurrogate(s.charAt(index + 1)));
+ }
+
  private static String replaceAll(Object[] objects) {
  return replace((String) objects[0], (String) objects[1], (String) objects[2], -1);
  }
@@ -504,6 +586,10 @@ private static String replace(String text, String searchString, String replaceme
  return sb.append(textCpa.slice(start, textCpa.length())).toString();
  }
 
+ private static String reverse(String s) {
+ return new StringBuilder(s).reverse().toString();
+ }
+
  private static List<String> split(String str, String separator) {
  return split(str, separator, Integer.MAX_VALUE);
  }

extensions/src/main/java/dev/cel/extensions/README.md

@@ -474,6 +474,19 @@ Examples:
  'TacoCat'.lowerAscii() // returns 'tacocat'
  'TacoCÆt Xii'.lowerAscii() // returns 'tacocÆt xii'
 
+### Quote
+
+Takes the given string and makes it safe to print (without any formatting due
+to escape sequences).
+If any invalid UTF-8 characters are encountered, they are replaced with \uFFFD.
+
+ strings.quote(<string>)
+
+Examples:
+
+ strings.quote('single-quote with "double quote"') // returns '"single-quote with \"double quote\""'
+ strings.quote("two escape sequences \a\n") // returns '"two escape sequences \\a\\n"'
+
 ### Replace
 
 Returns a new string based on the target, which replaces the occurrences of a
@@ -493,6 +506,20 @@ Examples:
  'hello hello'.replace('he', 'we', 1) // returns 'wello hello'
  'hello hello'.replace('he', 'we', 0) // returns 'hello hello'
 
+### Reverse
+
+Returns a new string whose characters are the same as the target string, only
+formatted in reverse order.
+This function relies on converting strings to Unicode code point arrays in
+order to reverse.
+
+ <string>.reverse() -> <string>
+
+Examples:
+
+ 'gums'.reverse() // returns 'smug'
+ 'John Smith'.reverse() // returns 'htimS nhoJ'
+
 ### Split
 
 Returns a mutable list of strings split from the input by the given separator. The

extensions/src/test/java/dev/cel/extensions/CelExtensionsTest.java

@@ -168,6 +168,7 @@ public void getAllFunctionNames() {
  "join",
  "lastIndexOf",
  "lowerAscii",
+ "strings.quote",
  "replace",
  "split",
  "substring",

extensions/src/test/java/dev/cel/extensions/CelStringExtensionsTest.java

@@ -33,6 +33,8 @@
 import dev.cel.runtime.CelEvaluationException;
 import dev.cel.runtime.CelRuntime;
 import dev.cel.runtime.CelRuntimeFactory;
+
+import java.nio.charset.StandardCharsets;
 import java.util.List;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -70,7 +72,9 @@ public void library() {
  "lastIndexOf",
  "lowerAscii",
  "replace",
+ "reverse",
  "split",
+ "strings.quote",
  "substring",
  "trim",
  "upperAscii");
@@ -1467,6 +1471,88 @@ public void stringExtension_functionSubset_success() throws Exception {
  assertThat(evaluatedResult).isEqualTo(true);
  }
 
+ @Test
+ @TestParameters("{string: 'abcd', expectedResult: 'dcba'}")
+ @TestParameters("{string: '', expectedResult: ''}")
+ @TestParameters("{string: 'a', expectedResult: 'a'}")
+ @TestParameters("{string: 'hello world', expectedResult: 'dlrow olleh'}")
+ @TestParameters("{string: 'ab가cd', expectedResult: 'dc가ba'}")
+ public void reverse_success(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("s.reverse()").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ @TestParameters("{string: '😁😑😦', expectedResult: '😦😑😁'}")
+ @TestParameters("{string: '\u180e\u200b\u200c\u200d\u2060\ufeff', expectedResult: '\ufeff\u2060\u200d\u200c\u200b\u180e'}")
+ public void reverse_unicode(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("s.reverse()").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ @TestParameters("{string: 'hello', expectedResult: '\"hello\"'}")
+ @TestParameters("{string: '', expectedResult: '\"\"'}")
+ @TestParameters("{string: 'contains \\\"quotes\\\"', expectedResult: '\"contains \\\\\\\"quotes\\\\\\\"\"'}")
+ @TestParameters("{string: 'ends with \\\\', expectedResult: '\"ends with \\\\\\\\\"'}")
+ @TestParameters("{string: '\\\\ starts with', expectedResult: '\"\\\\\\\\ starts with\"'}")
+ public void quote_success(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("strings.quote(s)").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ public void quote_singleWithDoubleQuotes() throws Exception {
+ String expr = "strings.quote('single-quote with \"double quote\"')";
+ String expected = "\"\\\"single-quote with \\\\\\\"double quote\\\\\\\"\\\"\"";
+ CelAbstractSyntaxTree ast = COMPILER.compile(expr + " == " + expected).getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval();
+
+ assertThat(evaluatedResult).isEqualTo(true);
+ }
+
+ @Test
+ public void quote_escapesSpecialCharacters() throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("strings.quote(s)").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult =
+ program.eval(
+ ImmutableMap.of(
+ "s", "\u0007bell\u000Bvtab\bback\ffeed\rret\nline\ttab\\slash 가 😁"));
+
+ assertThat(evaluatedResult)
+ .isEqualTo("\"\\abell\\vvtab\\bback\\ffeed\\rret\\nline\\ttab\\\\slash 가 😁\"");
+ }
+
+ @Test
+ public void quote_escapesMalformed_endWithHighSurrogate() throws Exception {
+ CelRuntime.Program program = RUNTIME.createProgram(COMPILER.compile("strings.quote(s)").getAst());
+ assertThat(program.eval(ImmutableMap.of("s", "end with high surrogate \uD83D")))
+ .isEqualTo("\"end with high surrogate \uFFFD\"");
+ }
+
+ @Test
+ public void quote_escapesMalformed_unpairedHighSurrogate() throws Exception {
+ CelRuntime.Program program = RUNTIME.createProgram(COMPILER.compile("strings.quote(s)").getAst());
+ assertThat(program.eval(ImmutableMap.of("s", "bad pair \uD83DA")))
+ .isEqualTo("\"bad pair \uFFFDA\"");
+ }
+
  @Test
  public void stringExtension_compileUnallowedFunction_throws() {
  CelCompiler celCompiler =

conformance/src/test/java/dev/cel/conformance/BUILD.bazel

@@ -119,8 +119,7 @@ _TESTS_TO_SKIP_LEGACY = [
 
  # Skip until fixed.
  "fields/qualified_identifier_resolution/map_value_repeat_key_heterogeneous",
- # TODO: Add strings.format and strings.quote.
- "string_ext/quote",
+ # TODO: Add strings.format.
  "string_ext/format",
  "string_ext/format_errors",
 
@@ -148,8 +147,7 @@ _TESTS_TO_SKIP_LEGACY = [
 ]
 
 _TESTS_TO_SKIP_PLANNER = [
- # TODO: Add strings.format and strings.quote.
- "string_ext/quote",
+ # TODO: Add strings.format.
  "string_ext/format",
  "string_ext/format_errors",
 

extensions/src/main/java/dev/cel/extensions/CelStringExtensions.java

@@ -137,6 +137,17 @@ public enum Function {
  SimpleType.STRING,
  SimpleType.STRING)),
  CelFunctionBinding.from("string_lower_ascii", String.class, Ascii::toLowerCase)),
+ QUOTE(
+ CelFunctionDecl.newFunctionDeclaration(
+ "strings.quote",
+ CelOverloadDecl.newGlobalOverload(
+ "strings_quote",
+ "Takes the given string and makes it safe to print (without any formatting"
+ + " due to escape sequences). If any invalid UTF-8 characters are"
+ + " encountered, they are replaced with \\uFFFD.",
+ SimpleType.STRING,
+ ImmutableList.of(SimpleType.STRING))),
+ CelFunctionBinding.from("strings_quote", String.class, CelStringExtensions::quote)),
  REPLACE(
  CelFunctionDecl.newFunctionDeclaration(
  "replace",
@@ -164,6 +175,16 @@ public enum Function {
  "string_replace_string_string_int",
  ImmutableList.of(String.class, String.class, String.class, Long.class),
  CelStringExtensions::replace)),
+ REVERSE(
+ CelFunctionDecl.newFunctionDeclaration(
+ "reverse",
+ CelOverloadDecl.newMemberOverload(
+ "string_reverse",
+ "Returns a new string whose characters are the same as the target string,"
+ + " only formatted in reverse order.",
+ SimpleType.STRING,
+ SimpleType.STRING)),
+ CelFunctionBinding.from("string_reverse", String.class, CelStringExtensions::reverse)),
  SPLIT(
  CelFunctionDecl.newFunctionDeclaration(
  "split",
@@ -449,6 +470,67 @@ private static Long lastIndexOf(CelCodePointArray str, CelCodePointArray substr,
  return -1L;
  }
 
+ private static String quote(String s) {
+ StringBuilder sb = new StringBuilder(s.length() + 2);
+ sb.append('"');
+ for (int i = 0; i < s.length(); ) {
+ int codePoint = s.codePointAt(i);
+ if (isMalformedUtf16(s, i, codePoint)) {
+ sb.append('\uFFFD');
+ i++;
+ continue;
+ }
+ switch (codePoint) {
+ case '\u0007':
+ sb.append("\\a");
+ break;
+ case '\b':
+ sb.append("\\b");
+ break;
+ case '\f':
+ sb.append("\\f");
+ break;
+ case '\n':
+ sb.append("\\n");
+ break;
+ case '\r':
+ sb.append("\\r");
+ break;
+ case '\t':
+ sb.append("\\t");
+ break;
+ case '\u000B':
+ sb.append("\\v");
+ break;
+ case '\\':
+ sb.append("\\\\");
+ break;
+ case '"':
+ sb.append("\\\"");
+ break;
+ default:
+ sb.appendCodePoint(codePoint);
+ break;
+ }
+ i += Character.charCount(codePoint);
+ }
+ sb.append('"');
+ return sb.toString();
+ }
+
+ private static boolean isMalformedUtf16(String s, int index, int codePoint) {
+ char currentChar = s.charAt(index);
+ if (!Character.isValidCodePoint(codePoint)) {
+ return true;
+ }
+ if (Character.isLowSurrogate(currentChar)) {
+ return true;
+ }
+ // Check for unpaired high surrogate
+ return Character.isHighSurrogate(currentChar)
+ && (index + 1 >= s.length() || !Character.isLowSurrogate(s.charAt(index + 1)));
+ }
+
  private static String replaceAll(Object[] objects) {
  return replace((String) objects[0], (String) objects[1], (String) objects[2], -1);
  }
@@ -504,6 +586,10 @@ private static String replace(String text, String searchString, String replaceme
  return sb.append(textCpa.slice(start, textCpa.length())).toString();
  }
 
+ private static String reverse(String s) {
+ return new StringBuilder(s).reverse().toString();
+ }
+
  private static List<String> split(String str, String separator) {
  return split(str, separator, Integer.MAX_VALUE);
  }

extensions/src/main/java/dev/cel/extensions/README.md

@@ -474,6 +474,19 @@ Examples:
  'TacoCat'.lowerAscii() // returns 'tacocat'
  'TacoCÆt Xii'.lowerAscii() // returns 'tacocÆt xii'
 
+### Quote
+
+Takes the given string and makes it safe to print (without any formatting due
+to escape sequences).
+If any invalid UTF-8 characters are encountered, they are replaced with \uFFFD.
+
+ strings.quote(<string>)
+
+Examples:
+
+ strings.quote('single-quote with "double quote"') // returns '"single-quote with \"double quote\""'
+ strings.quote("two escape sequences \a\n") // returns '"two escape sequences \\a\\n"'
+
 ### Replace
 
 Returns a new string based on the target, which replaces the occurrences of a
@@ -493,6 +506,20 @@ Examples:
  'hello hello'.replace('he', 'we', 1) // returns 'wello hello'
  'hello hello'.replace('he', 'we', 0) // returns 'hello hello'
 
+### Reverse
+
+Returns a new string whose characters are the same as the target string, only
+formatted in reverse order.
+This function relies on converting strings to Unicode code point arrays in
+order to reverse.
+
+ <string>.reverse() -> <string>
+
+Examples:
+
+ 'gums'.reverse() // returns 'smug'
+ 'John Smith'.reverse() // returns 'htimS nhoJ'
+
 ### Split
 
 Returns a mutable list of strings split from the input by the given separator. The

extensions/src/test/java/dev/cel/extensions/CelExtensionsTest.java

@@ -168,6 +168,7 @@ public void getAllFunctionNames() {
  "join",
  "lastIndexOf",
  "lowerAscii",
+ "strings.quote",
  "replace",
  "split",
  "substring",

extensions/src/test/java/dev/cel/extensions/CelStringExtensionsTest.java

@@ -33,6 +33,8 @@
 import dev.cel.runtime.CelEvaluationException;
 import dev.cel.runtime.CelRuntime;
 import dev.cel.runtime.CelRuntimeFactory;
+
+import java.nio.charset.StandardCharsets;
 import java.util.List;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -70,7 +72,9 @@ public void library() {
  "lastIndexOf",
  "lowerAscii",
  "replace",
+ "reverse",
  "split",
+ "strings.quote",
  "substring",
  "trim",
  "upperAscii");
@@ -1467,6 +1471,88 @@ public void stringExtension_functionSubset_success() throws Exception {
  assertThat(evaluatedResult).isEqualTo(true);
  }
 
+ @Test
+ @TestParameters("{string: 'abcd', expectedResult: 'dcba'}")
+ @TestParameters("{string: '', expectedResult: ''}")
+ @TestParameters("{string: 'a', expectedResult: 'a'}")
+ @TestParameters("{string: 'hello world', expectedResult: 'dlrow olleh'}")
+ @TestParameters("{string: 'ab가cd', expectedResult: 'dc가ba'}")
+ public void reverse_success(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("s.reverse()").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ @TestParameters("{string: '😁😑😦', expectedResult: '😦😑😁'}")
+ @TestParameters("{string: '\u180e\u200b\u200c\u200d\u2060\ufeff', expectedResult: '\ufeff\u2060\u200d\u200c\u200b\u180e'}")
+ public void reverse_unicode(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("s.reverse()").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ @TestParameters("{string: 'hello', expectedResult: '\"hello\"'}")
+ @TestParameters("{string: '', expectedResult: '\"\"'}")
+ @TestParameters("{string: 'contains \\\"quotes\\\"', expectedResult: '\"contains \\\\\\\"quotes\\\\\\\"\"'}")
+ @TestParameters("{string: 'ends with \\\\', expectedResult: '\"ends with \\\\\\\\\"'}")
+ @TestParameters("{string: '\\\\ starts with', expectedResult: '\"\\\\\\\\ starts with\"'}")
+ public void quote_success(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("strings.quote(s)").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ public void quote_singleWithDoubleQuotes() throws Exception {
+ String expr = "strings.quote('single-quote with \"double quote\"')";
+ String expected = "\"\\\"single-quote with \\\\\\\"double quote\\\\\\\"\\\"\"";
+ CelAbstractSyntaxTree ast = COMPILER.compile(expr + " == " + expected).getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval();
+
+ assertThat(evaluatedResult).isEqualTo(true);
+ }
+
+ @Test
+ public void quote_escapesSpecialCharacters() throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("strings.quote(s)").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult =
+ program.eval(
+ ImmutableMap.of(
+ "s", "\u0007bell\u000Bvtab\bback\ffeed\rret\nline\ttab\\slash 가 😁"));
+
+ assertThat(evaluatedResult)
+ .isEqualTo("\"\\abell\\vvtab\\bback\\ffeed\\rret\\nline\\ttab\\\\slash 가 😁\"");
+ }
+
+ @Test
+ public void quote_escapesMalformed_endWithHighSurrogate() throws Exception {
+ CelRuntime.Program program = RUNTIME.createProgram(COMPILER.compile("strings.quote(s)").getAst());
+ assertThat(program.eval(ImmutableMap.of("s", "end with high surrogate \uD83D")))
+ .isEqualTo("\"end with high surrogate \uFFFD\"");
+ }
+
+ @Test
+ public void quote_escapesMalformed_unpairedHighSurrogate() throws Exception {
+ CelRuntime.Program program = RUNTIME.createProgram(COMPILER.compile("strings.quote(s)").getAst());
+ assertThat(program.eval(ImmutableMap.of("s", "bad pair \uD83DA")))
+ .isEqualTo("\"bad pair \uFFFDA\"");
+ }
+
  @Test
  public void stringExtension_compileUnallowedFunction_throws() {
  CelCompiler celCompiler =

conformance/src/test/java/dev/cel/conformance/BUILD.bazel

@@ -119,8 +119,7 @@ _TESTS_TO_SKIP_LEGACY = [
 
  # Skip until fixed.
  "fields/qualified_identifier_resolution/map_value_repeat_key_heterogeneous",
- # TODO: Add strings.format and strings.quote.
- "string_ext/quote",
+ # TODO: Add strings.format.
  "string_ext/format",
  "string_ext/format_errors",
 
@@ -148,8 +147,7 @@ _TESTS_TO_SKIP_LEGACY = [
 ]
 
 _TESTS_TO_SKIP_PLANNER = [
- # TODO: Add strings.format and strings.quote.
- "string_ext/quote",
+ # TODO: Add strings.format.
  "string_ext/format",
  "string_ext/format_errors",
 

extensions/src/main/java/dev/cel/extensions/CelStringExtensions.java

@@ -137,6 +137,17 @@ public enum Function {
  SimpleType.STRING,
  SimpleType.STRING)),
  CelFunctionBinding.from("string_lower_ascii", String.class, Ascii::toLowerCase)),
+ QUOTE(
+ CelFunctionDecl.newFunctionDeclaration(
+ "strings.quote",
+ CelOverloadDecl.newGlobalOverload(
+ "strings_quote",
+ "Takes the given string and makes it safe to print (without any formatting"
+ + " due to escape sequences). If any invalid UTF-8 characters are"
+ + " encountered, they are replaced with \\uFFFD.",
+ SimpleType.STRING,
+ ImmutableList.of(SimpleType.STRING))),
+ CelFunctionBinding.from("strings_quote", String.class, CelStringExtensions::quote)),
  REPLACE(
  CelFunctionDecl.newFunctionDeclaration(
  "replace",
@@ -164,6 +175,16 @@ public enum Function {
  "string_replace_string_string_int",
  ImmutableList.of(String.class, String.class, String.class, Long.class),
  CelStringExtensions::replace)),
+ REVERSE(
+ CelFunctionDecl.newFunctionDeclaration(
+ "reverse",
+ CelOverloadDecl.newMemberOverload(
+ "string_reverse",
+ "Returns a new string whose characters are the same as the target string,"
+ + " only formatted in reverse order.",
+ SimpleType.STRING,
+ SimpleType.STRING)),
+ CelFunctionBinding.from("string_reverse", String.class, CelStringExtensions::reverse)),
  SPLIT(
  CelFunctionDecl.newFunctionDeclaration(
  "split",
@@ -449,6 +470,67 @@ private static Long lastIndexOf(CelCodePointArray str, CelCodePointArray substr,
  return -1L;
  }
 
+ private static String quote(String s) {
+ StringBuilder sb = new StringBuilder(s.length() + 2);
+ sb.append('"');
+ for (int i = 0; i < s.length(); ) {
+ int codePoint = s.codePointAt(i);
+ if (isMalformedUtf16(s, i, codePoint)) {
+ sb.append('\uFFFD');
+ i++;
+ continue;
+ }
+ switch (codePoint) {
+ case '\u0007':
+ sb.append("\\a");
+ break;
+ case '\b':
+ sb.append("\\b");
+ break;
+ case '\f':
+ sb.append("\\f");
+ break;
+ case '\n':
+ sb.append("\\n");
+ break;
+ case '\r':
+ sb.append("\\r");
+ break;
+ case '\t':
+ sb.append("\\t");
+ break;
+ case '\u000B':
+ sb.append("\\v");
+ break;
+ case '\\':
+ sb.append("\\\\");
+ break;
+ case '"':
+ sb.append("\\\"");
+ break;
+ default:
+ sb.appendCodePoint(codePoint);
+ break;
+ }
+ i += Character.charCount(codePoint);
+ }
+ sb.append('"');
+ return sb.toString();
+ }
+
+ private static boolean isMalformedUtf16(String s, int index, int codePoint) {
+ char currentChar = s.charAt(index);
+ if (!Character.isValidCodePoint(codePoint)) {
+ return true;
+ }
+ if (Character.isLowSurrogate(currentChar)) {
+ return true;
+ }
+ // Check for unpaired high surrogate
+ return Character.isHighSurrogate(currentChar)
+ && (index + 1 >= s.length() || !Character.isLowSurrogate(s.charAt(index + 1)));
+ }
+
  private static String replaceAll(Object[] objects) {
  return replace((String) objects[0], (String) objects[1], (String) objects[2], -1);
  }
@@ -504,6 +586,10 @@ private static String replace(String text, String searchString, String replaceme
  return sb.append(textCpa.slice(start, textCpa.length())).toString();
  }
 
+ private static String reverse(String s) {
+ return new StringBuilder(s).reverse().toString();
+ }
+
  private static List<String> split(String str, String separator) {
  return split(str, separator, Integer.MAX_VALUE);
  }

extensions/src/main/java/dev/cel/extensions/README.md

@@ -474,6 +474,19 @@ Examples:
  'TacoCat'.lowerAscii() // returns 'tacocat'
  'TacoCÆt Xii'.lowerAscii() // returns 'tacocÆt xii'
 
+### Quote
+
+Takes the given string and makes it safe to print (without any formatting due
+to escape sequences).
+If any invalid UTF-8 characters are encountered, they are replaced with \uFFFD.
+
+ strings.quote(<string>)
+
+Examples:
+
+ strings.quote('single-quote with "double quote"') // returns '"single-quote with \"double quote\""'
+ strings.quote("two escape sequences \a\n") // returns '"two escape sequences \\a\\n"'
+
 ### Replace
 
 Returns a new string based on the target, which replaces the occurrences of a
@@ -493,6 +506,20 @@ Examples:
  'hello hello'.replace('he', 'we', 1) // returns 'wello hello'
  'hello hello'.replace('he', 'we', 0) // returns 'hello hello'
 
+### Reverse
+
+Returns a new string whose characters are the same as the target string, only
+formatted in reverse order.
+This function relies on converting strings to Unicode code point arrays in
+order to reverse.
+
+ <string>.reverse() -> <string>
+
+Examples:
+
+ 'gums'.reverse() // returns 'smug'
+ 'John Smith'.reverse() // returns 'htimS nhoJ'
+
 ### Split
 
 Returns a mutable list of strings split from the input by the given separator. The

extensions/src/test/java/dev/cel/extensions/CelExtensionsTest.java

@@ -168,6 +168,7 @@ public void getAllFunctionNames() {
  "join",
  "lastIndexOf",
  "lowerAscii",
+ "strings.quote",
  "replace",
  "split",
  "substring",

extensions/src/test/java/dev/cel/extensions/CelStringExtensionsTest.java

@@ -33,6 +33,8 @@
 import dev.cel.runtime.CelEvaluationException;
 import dev.cel.runtime.CelRuntime;
 import dev.cel.runtime.CelRuntimeFactory;
+
+import java.nio.charset.StandardCharsets;
 import java.util.List;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -70,7 +72,9 @@ public void library() {
  "lastIndexOf",
  "lowerAscii",
  "replace",
+ "reverse",
  "split",
+ "strings.quote",
  "substring",
  "trim",
  "upperAscii");
@@ -1467,6 +1471,88 @@ public void stringExtension_functionSubset_success() throws Exception {
  assertThat(evaluatedResult).isEqualTo(true);
  }
 
+ @Test
+ @TestParameters("{string: 'abcd', expectedResult: 'dcba'}")
+ @TestParameters("{string: '', expectedResult: ''}")
+ @TestParameters("{string: 'a', expectedResult: 'a'}")
+ @TestParameters("{string: 'hello world', expectedResult: 'dlrow olleh'}")
+ @TestParameters("{string: 'ab가cd', expectedResult: 'dc가ba'}")
+ public void reverse_success(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("s.reverse()").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ @TestParameters("{string: '😁😑😦', expectedResult: '😦😑😁'}")
+ @TestParameters("{string: '\u180e\u200b\u200c\u200d\u2060\ufeff', expectedResult: '\ufeff\u2060\u200d\u200c\u200b\u180e'}")
+ public void reverse_unicode(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("s.reverse()").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ @TestParameters("{string: 'hello', expectedResult: '\"hello\"'}")
+ @TestParameters("{string: '', expectedResult: '\"\"'}")
+ @TestParameters("{string: 'contains \\\"quotes\\\"', expectedResult: '\"contains \\\\\\\"quotes\\\\\\\"\"'}")
+ @TestParameters("{string: 'ends with \\\\', expectedResult: '\"ends with \\\\\\\\\"'}")
+ @TestParameters("{string: '\\\\ starts with', expectedResult: '\"\\\\\\\\ starts with\"'}")
+ public void quote_success(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("strings.quote(s)").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ public void quote_singleWithDoubleQuotes() throws Exception {
+ String expr = "strings.quote('single-quote with \"double quote\"')";
+ String expected = "\"\\\"single-quote with \\\\\\\"double quote\\\\\\\"\\\"\"";
+ CelAbstractSyntaxTree ast = COMPILER.compile(expr + " == " + expected).getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval();
+
+ assertThat(evaluatedResult).isEqualTo(true);
+ }
+
+ @Test
+ public void quote_escapesSpecialCharacters() throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("strings.quote(s)").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult =
+ program.eval(
+ ImmutableMap.of(
+ "s", "\u0007bell\u000Bvtab\bback\ffeed\rret\nline\ttab\\slash 가 😁"));
+
+ assertThat(evaluatedResult)
+ .isEqualTo("\"\\abell\\vvtab\\bback\\ffeed\\rret\\nline\\ttab\\\\slash 가 😁\"");
+ }
+
+ @Test
+ public void quote_escapesMalformed_endWithHighSurrogate() throws Exception {
+ CelRuntime.Program program = RUNTIME.createProgram(COMPILER.compile("strings.quote(s)").getAst());
+ assertThat(program.eval(ImmutableMap.of("s", "end with high surrogate \uD83D")))
+ .isEqualTo("\"end with high surrogate \uFFFD\"");
+ }
+
+ @Test
+ public void quote_escapesMalformed_unpairedHighSurrogate() throws Exception {
+ CelRuntime.Program program = RUNTIME.createProgram(COMPILER.compile("strings.quote(s)").getAst());
+ assertThat(program.eval(ImmutableMap.of("s", "bad pair \uD83DA")))
+ .isEqualTo("\"bad pair \uFFFDA\"");
+ }
+
  @Test
  public void stringExtension_compileUnallowedFunction_throws() {
  CelCompiler celCompiler =

conformance/src/test/java/dev/cel/conformance/BUILD.bazel

@@ -119,8 +119,7 @@ _TESTS_TO_SKIP_LEGACY = [
 
  # Skip until fixed.
  "fields/qualified_identifier_resolution/map_value_repeat_key_heterogeneous",
- # TODO: Add strings.format and strings.quote.
- "string_ext/quote",
+ # TODO: Add strings.format.
  "string_ext/format",
  "string_ext/format_errors",
 
@@ -148,8 +147,7 @@ _TESTS_TO_SKIP_LEGACY = [
 ]
 
 _TESTS_TO_SKIP_PLANNER = [
- # TODO: Add strings.format and strings.quote.
- "string_ext/quote",
+ # TODO: Add strings.format.
  "string_ext/format",
  "string_ext/format_errors",
 

extensions/src/main/java/dev/cel/extensions/CelStringExtensions.java

@@ -137,6 +137,17 @@ public enum Function {
  SimpleType.STRING,
  SimpleType.STRING)),
  CelFunctionBinding.from("string_lower_ascii", String.class, Ascii::toLowerCase)),
+ QUOTE(
+ CelFunctionDecl.newFunctionDeclaration(
+ "strings.quote",
+ CelOverloadDecl.newGlobalOverload(
+ "strings_quote",
+ "Takes the given string and makes it safe to print (without any formatting"
+ + " due to escape sequences). If any invalid UTF-8 characters are"
+ + " encountered, they are replaced with \\uFFFD.",
+ SimpleType.STRING,
+ ImmutableList.of(SimpleType.STRING))),
+ CelFunctionBinding.from("strings_quote", String.class, CelStringExtensions::quote)),
  REPLACE(
  CelFunctionDecl.newFunctionDeclaration(
  "replace",
@@ -164,6 +175,16 @@ public enum Function {
  "string_replace_string_string_int",
  ImmutableList.of(String.class, String.class, String.class, Long.class),
  CelStringExtensions::replace)),
+ REVERSE(
+ CelFunctionDecl.newFunctionDeclaration(
+ "reverse",
+ CelOverloadDecl.newMemberOverload(
+ "string_reverse",
+ "Returns a new string whose characters are the same as the target string,"
+ + " only formatted in reverse order.",
+ SimpleType.STRING,
+ SimpleType.STRING)),
+ CelFunctionBinding.from("string_reverse", String.class, CelStringExtensions::reverse)),
  SPLIT(
  CelFunctionDecl.newFunctionDeclaration(
  "split",
@@ -449,6 +470,67 @@ private static Long lastIndexOf(CelCodePointArray str, CelCodePointArray substr,
  return -1L;
  }
 
+ private static String quote(String s) {
+ StringBuilder sb = new StringBuilder(s.length() + 2);
+ sb.append('"');
+ for (int i = 0; i < s.length(); ) {
+ int codePoint = s.codePointAt(i);
+ if (isMalformedUtf16(s, i, codePoint)) {
+ sb.append('\uFFFD');
+ i++;
+ continue;
+ }
+ switch (codePoint) {
+ case '\u0007':
+ sb.append("\\a");
+ break;
+ case '\b':
+ sb.append("\\b");
+ break;
+ case '\f':
+ sb.append("\\f");
+ break;
+ case '\n':
+ sb.append("\\n");
+ break;
+ case '\r':
+ sb.append("\\r");
+ break;
+ case '\t':
+ sb.append("\\t");
+ break;
+ case '\u000B':
+ sb.append("\\v");
+ break;
+ case '\\':
+ sb.append("\\\\");
+ break;
+ case '"':
+ sb.append("\\\"");
+ break;
+ default:
+ sb.appendCodePoint(codePoint);
+ break;
+ }
+ i += Character.charCount(codePoint);
+ }
+ sb.append('"');
+ return sb.toString();
+ }
+
+ private static boolean isMalformedUtf16(String s, int index, int codePoint) {
+ char currentChar = s.charAt(index);
+ if (!Character.isValidCodePoint(codePoint)) {
+ return true;
+ }
+ if (Character.isLowSurrogate(currentChar)) {
+ return true;
+ }
+ // Check for unpaired high surrogate
+ return Character.isHighSurrogate(currentChar)
+ && (index + 1 >= s.length() || !Character.isLowSurrogate(s.charAt(index + 1)));
+ }
+
  private static String replaceAll(Object[] objects) {
  return replace((String) objects[0], (String) objects[1], (String) objects[2], -1);
  }
@@ -504,6 +586,10 @@ private static String replace(String text, String searchString, String replaceme
  return sb.append(textCpa.slice(start, textCpa.length())).toString();
  }
 
+ private static String reverse(String s) {
+ return new StringBuilder(s).reverse().toString();
+ }
+
  private static List<String> split(String str, String separator) {
  return split(str, separator, Integer.MAX_VALUE);
  }

extensions/src/main/java/dev/cel/extensions/README.md

@@ -474,6 +474,19 @@ Examples:
  'TacoCat'.lowerAscii() // returns 'tacocat'
  'TacoCÆt Xii'.lowerAscii() // returns 'tacocÆt xii'
 
+### Quote
+
+Takes the given string and makes it safe to print (without any formatting due
+to escape sequences).
+If any invalid UTF-8 characters are encountered, they are replaced with \uFFFD.
+
+ strings.quote(<string>)
+
+Examples:
+
+ strings.quote('single-quote with "double quote"') // returns '"single-quote with \"double quote\""'
+ strings.quote("two escape sequences \a\n") // returns '"two escape sequences \\a\\n"'
+
 ### Replace
 
 Returns a new string based on the target, which replaces the occurrences of a
@@ -493,6 +506,20 @@ Examples:
  'hello hello'.replace('he', 'we', 1) // returns 'wello hello'
  'hello hello'.replace('he', 'we', 0) // returns 'hello hello'
 
+### Reverse
+
+Returns a new string whose characters are the same as the target string, only
+formatted in reverse order.
+This function relies on converting strings to Unicode code point arrays in
+order to reverse.
+
+ <string>.reverse() -> <string>
+
+Examples:
+
+ 'gums'.reverse() // returns 'smug'
+ 'John Smith'.reverse() // returns 'htimS nhoJ'
+
 ### Split
 
 Returns a mutable list of strings split from the input by the given separator. The

extensions/src/test/java/dev/cel/extensions/CelExtensionsTest.java

@@ -168,6 +168,7 @@ public void getAllFunctionNames() {
  "join",
  "lastIndexOf",
  "lowerAscii",
+ "strings.quote",
  "replace",
  "split",
  "substring",

extensions/src/test/java/dev/cel/extensions/CelStringExtensionsTest.java

@@ -33,6 +33,8 @@
 import dev.cel.runtime.CelEvaluationException;
 import dev.cel.runtime.CelRuntime;
 import dev.cel.runtime.CelRuntimeFactory;
+
+import java.nio.charset.StandardCharsets;
 import java.util.List;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -70,7 +72,9 @@ public void library() {
  "lastIndexOf",
  "lowerAscii",
  "replace",
+ "reverse",
  "split",
+ "strings.quote",
  "substring",
  "trim",
  "upperAscii");
@@ -1467,6 +1471,88 @@ public void stringExtension_functionSubset_success() throws Exception {
  assertThat(evaluatedResult).isEqualTo(true);
  }
 
+ @Test
+ @TestParameters("{string: 'abcd', expectedResult: 'dcba'}")
+ @TestParameters("{string: '', expectedResult: ''}")
+ @TestParameters("{string: 'a', expectedResult: 'a'}")
+ @TestParameters("{string: 'hello world', expectedResult: 'dlrow olleh'}")
+ @TestParameters("{string: 'ab가cd', expectedResult: 'dc가ba'}")
+ public void reverse_success(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("s.reverse()").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ @TestParameters("{string: '😁😑😦', expectedResult: '😦😑😁'}")
+ @TestParameters("{string: '\u180e\u200b\u200c\u200d\u2060\ufeff', expectedResult: '\ufeff\u2060\u200d\u200c\u200b\u180e'}")
+ public void reverse_unicode(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("s.reverse()").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ @TestParameters("{string: 'hello', expectedResult: '\"hello\"'}")
+ @TestParameters("{string: '', expectedResult: '\"\"'}")
+ @TestParameters("{string: 'contains \\\"quotes\\\"', expectedResult: '\"contains \\\\\\\"quotes\\\\\\\"\"'}")
+ @TestParameters("{string: 'ends with \\\\', expectedResult: '\"ends with \\\\\\\\\"'}")
+ @TestParameters("{string: '\\\\ starts with', expectedResult: '\"\\\\\\\\ starts with\"'}")
+ public void quote_success(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("strings.quote(s)").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ public void quote_singleWithDoubleQuotes() throws Exception {
+ String expr = "strings.quote('single-quote with \"double quote\"')";
+ String expected = "\"\\\"single-quote with \\\\\\\"double quote\\\\\\\"\\\"\"";
+ CelAbstractSyntaxTree ast = COMPILER.compile(expr + " == " + expected).getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval();
+
+ assertThat(evaluatedResult).isEqualTo(true);
+ }
+
+ @Test
+ public void quote_escapesSpecialCharacters() throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("strings.quote(s)").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult =
+ program.eval(
+ ImmutableMap.of(
+ "s", "\u0007bell\u000Bvtab\bback\ffeed\rret\nline\ttab\\slash 가 😁"));
+
+ assertThat(evaluatedResult)
+ .isEqualTo("\"\\abell\\vvtab\\bback\\ffeed\\rret\\nline\\ttab\\\\slash 가 😁\"");
+ }
+
+ @Test
+ public void quote_escapesMalformed_endWithHighSurrogate() throws Exception {
+ CelRuntime.Program program = RUNTIME.createProgram(COMPILER.compile("strings.quote(s)").getAst());
+ assertThat(program.eval(ImmutableMap.of("s", "end with high surrogate \uD83D")))
+ .isEqualTo("\"end with high surrogate \uFFFD\"");
+ }
+
+ @Test
+ public void quote_escapesMalformed_unpairedHighSurrogate() throws Exception {
+ CelRuntime.Program program = RUNTIME.createProgram(COMPILER.compile("strings.quote(s)").getAst());
+ assertThat(program.eval(ImmutableMap.of("s", "bad pair \uD83DA")))
+ .isEqualTo("\"bad pair \uFFFDA\"");
+ }
+
  @Test
  public void stringExtension_compileUnallowedFunction_throws() {
  CelCompiler celCompiler =

conformance/src/test/java/dev/cel/conformance/BUILD.bazel

@@ -119,8 +119,7 @@ _TESTS_TO_SKIP_LEGACY = [
 
  # Skip until fixed.
  "fields/qualified_identifier_resolution/map_value_repeat_key_heterogeneous",
- # TODO: Add strings.format and strings.quote.
- "string_ext/quote",
+ # TODO: Add strings.format.
  "string_ext/format",
  "string_ext/format_errors",
 
@@ -148,8 +147,7 @@ _TESTS_TO_SKIP_LEGACY = [
 ]
 
 _TESTS_TO_SKIP_PLANNER = [
- # TODO: Add strings.format and strings.quote.
- "string_ext/quote",
+ # TODO: Add strings.format.
  "string_ext/format",
  "string_ext/format_errors",
 

extensions/src/main/java/dev/cel/extensions/CelStringExtensions.java

@@ -137,6 +137,17 @@ public enum Function {
  SimpleType.STRING,
  SimpleType.STRING)),
  CelFunctionBinding.from("string_lower_ascii", String.class, Ascii::toLowerCase)),
+ QUOTE(
+ CelFunctionDecl.newFunctionDeclaration(
+ "strings.quote",
+ CelOverloadDecl.newGlobalOverload(
+ "strings_quote",
+ "Takes the given string and makes it safe to print (without any formatting"
+ + " due to escape sequences). If any invalid UTF-8 characters are"
+ + " encountered, they are replaced with \\uFFFD.",
+ SimpleType.STRING,
+ ImmutableList.of(SimpleType.STRING))),
+ CelFunctionBinding.from("strings_quote", String.class, CelStringExtensions::quote)),
  REPLACE(
  CelFunctionDecl.newFunctionDeclaration(
  "replace",
@@ -164,6 +175,16 @@ public enum Function {
  "string_replace_string_string_int",
  ImmutableList.of(String.class, String.class, String.class, Long.class),
  CelStringExtensions::replace)),
+ REVERSE(
+ CelFunctionDecl.newFunctionDeclaration(
+ "reverse",
+ CelOverloadDecl.newMemberOverload(
+ "string_reverse",
+ "Returns a new string whose characters are the same as the target string,"
+ + " only formatted in reverse order.",
+ SimpleType.STRING,
+ SimpleType.STRING)),
+ CelFunctionBinding.from("string_reverse", String.class, CelStringExtensions::reverse)),
  SPLIT(
  CelFunctionDecl.newFunctionDeclaration(
  "split",
@@ -449,6 +470,67 @@ private static Long lastIndexOf(CelCodePointArray str, CelCodePointArray substr,
  return -1L;
  }
 
+ private static String quote(String s) {
+ StringBuilder sb = new StringBuilder(s.length() + 2);
+ sb.append('"');
+ for (int i = 0; i < s.length(); ) {
+ int codePoint = s.codePointAt(i);
+ if (isMalformedUtf16(s, i, codePoint)) {
+ sb.append('\uFFFD');
+ i++;
+ continue;
+ }
+ switch (codePoint) {
+ case '\u0007':
+ sb.append("\\a");
+ break;
+ case '\b':
+ sb.append("\\b");
+ break;
+ case '\f':
+ sb.append("\\f");
+ break;
+ case '\n':
+ sb.append("\\n");
+ break;
+ case '\r':
+ sb.append("\\r");
+ break;
+ case '\t':
+ sb.append("\\t");
+ break;
+ case '\u000B':
+ sb.append("\\v");
+ break;
+ case '\\':
+ sb.append("\\\\");
+ break;
+ case '"':
+ sb.append("\\\"");
+ break;
+ default:
+ sb.appendCodePoint(codePoint);
+ break;
+ }
+ i += Character.charCount(codePoint);
+ }
+ sb.append('"');
+ return sb.toString();
+ }
+
+ private static boolean isMalformedUtf16(String s, int index, int codePoint) {
+ char currentChar = s.charAt(index);
+ if (!Character.isValidCodePoint(codePoint)) {
+ return true;
+ }
+ if (Character.isLowSurrogate(currentChar)) {
+ return true;
+ }
+ // Check for unpaired high surrogate
+ return Character.isHighSurrogate(currentChar)
+ && (index + 1 >= s.length() || !Character.isLowSurrogate(s.charAt(index + 1)));
+ }
+
  private static String replaceAll(Object[] objects) {
  return replace((String) objects[0], (String) objects[1], (String) objects[2], -1);
  }
@@ -504,6 +586,10 @@ private static String replace(String text, String searchString, String replaceme
  return sb.append(textCpa.slice(start, textCpa.length())).toString();
  }
 
+ private static String reverse(String s) {
+ return new StringBuilder(s).reverse().toString();
+ }
+
  private static List<String> split(String str, String separator) {
  return split(str, separator, Integer.MAX_VALUE);
  }

extensions/src/main/java/dev/cel/extensions/README.md

@@ -474,6 +474,19 @@ Examples:
  'TacoCat'.lowerAscii() // returns 'tacocat'
  'TacoCÆt Xii'.lowerAscii() // returns 'tacocÆt xii'
 
+### Quote
+
+Takes the given string and makes it safe to print (without any formatting due
+to escape sequences).
+If any invalid UTF-8 characters are encountered, they are replaced with \uFFFD.
+
+ strings.quote(<string>)
+
+Examples:
+
+ strings.quote('single-quote with "double quote"') // returns '"single-quote with \"double quote\""'
+ strings.quote("two escape sequences \a\n") // returns '"two escape sequences \\a\\n"'
+
 ### Replace
 
 Returns a new string based on the target, which replaces the occurrences of a
@@ -493,6 +506,20 @@ Examples:
  'hello hello'.replace('he', 'we', 1) // returns 'wello hello'
  'hello hello'.replace('he', 'we', 0) // returns 'hello hello'
 
+### Reverse
+
+Returns a new string whose characters are the same as the target string, only
+formatted in reverse order.
+This function relies on converting strings to Unicode code point arrays in
+order to reverse.
+
+ <string>.reverse() -> <string>
+
+Examples:
+
+ 'gums'.reverse() // returns 'smug'
+ 'John Smith'.reverse() // returns 'htimS nhoJ'
+
 ### Split
 
 Returns a mutable list of strings split from the input by the given separator. The

extensions/src/test/java/dev/cel/extensions/CelExtensionsTest.java

@@ -168,6 +168,7 @@ public void getAllFunctionNames() {
  "join",
  "lastIndexOf",
  "lowerAscii",
+ "strings.quote",
  "replace",
  "split",
  "substring",

extensions/src/test/java/dev/cel/extensions/CelStringExtensionsTest.java

@@ -33,6 +33,8 @@
 import dev.cel.runtime.CelEvaluationException;
 import dev.cel.runtime.CelRuntime;
 import dev.cel.runtime.CelRuntimeFactory;
+
+import java.nio.charset.StandardCharsets;
 import java.util.List;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -70,7 +72,9 @@ public void library() {
  "lastIndexOf",
  "lowerAscii",
  "replace",
+ "reverse",
  "split",
+ "strings.quote",
  "substring",
  "trim",
  "upperAscii");
@@ -1467,6 +1471,88 @@ public void stringExtension_functionSubset_success() throws Exception {
  assertThat(evaluatedResult).isEqualTo(true);
  }
 
+ @Test
+ @TestParameters("{string: 'abcd', expectedResult: 'dcba'}")
+ @TestParameters("{string: '', expectedResult: ''}")
+ @TestParameters("{string: 'a', expectedResult: 'a'}")
+ @TestParameters("{string: 'hello world', expectedResult: 'dlrow olleh'}")
+ @TestParameters("{string: 'ab가cd', expectedResult: 'dc가ba'}")
+ public void reverse_success(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("s.reverse()").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ @TestParameters("{string: '😁😑😦', expectedResult: '😦😑😁'}")
+ @TestParameters("{string: '\u180e\u200b\u200c\u200d\u2060\ufeff', expectedResult: '\ufeff\u2060\u200d\u200c\u200b\u180e'}")
+ public void reverse_unicode(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("s.reverse()").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ @TestParameters("{string: 'hello', expectedResult: '\"hello\"'}")
+ @TestParameters("{string: '', expectedResult: '\"\"'}")
+ @TestParameters("{string: 'contains \\\"quotes\\\"', expectedResult: '\"contains \\\\\\\"quotes\\\\\\\"\"'}")
+ @TestParameters("{string: 'ends with \\\\', expectedResult: '\"ends with \\\\\\\\\"'}")
+ @TestParameters("{string: '\\\\ starts with', expectedResult: '\"\\\\\\\\ starts with\"'}")
+ public void quote_success(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("strings.quote(s)").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ public void quote_singleWithDoubleQuotes() throws Exception {
+ String expr = "strings.quote('single-quote with \"double quote\"')";
+ String expected = "\"\\\"single-quote with \\\\\\\"double quote\\\\\\\"\\\"\"";
+ CelAbstractSyntaxTree ast = COMPILER.compile(expr + " == " + expected).getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval();
+
+ assertThat(evaluatedResult).isEqualTo(true);
+ }
+
+ @Test
+ public void quote_escapesSpecialCharacters() throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("strings.quote(s)").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult =
+ program.eval(
+ ImmutableMap.of(
+ "s", "\u0007bell\u000Bvtab\bback\ffeed\rret\nline\ttab\\slash 가 😁"));
+
+ assertThat(evaluatedResult)
+ .isEqualTo("\"\\abell\\vvtab\\bback\\ffeed\\rret\\nline\\ttab\\\\slash 가 😁\"");
+ }
+
+ @Test
+ public void quote_escapesMalformed_endWithHighSurrogate() throws Exception {
+ CelRuntime.Program program = RUNTIME.createProgram(COMPILER.compile("strings.quote(s)").getAst());
+ assertThat(program.eval(ImmutableMap.of("s", "end with high surrogate \uD83D")))
+ .isEqualTo("\"end with high surrogate \uFFFD\"");
+ }
+
+ @Test
+ public void quote_escapesMalformed_unpairedHighSurrogate() throws Exception {
+ CelRuntime.Program program = RUNTIME.createProgram(COMPILER.compile("strings.quote(s)").getAst());
+ assertThat(program.eval(ImmutableMap.of("s", "bad pair \uD83DA")))
+ .isEqualTo("\"bad pair \uFFFDA\"");
+ }
+
  @Test
  public void stringExtension_compileUnallowedFunction_throws() {
  CelCompiler celCompiler =

conformance/src/test/java/dev/cel/conformance/BUILD.bazel

@@ -119,8 +119,7 @@ _TESTS_TO_SKIP_LEGACY = [
 
  # Skip until fixed.
  "fields/qualified_identifier_resolution/map_value_repeat_key_heterogeneous",
- # TODO: Add strings.format and strings.quote.
- "string_ext/quote",
+ # TODO: Add strings.format.
  "string_ext/format",
  "string_ext/format_errors",
 
@@ -148,8 +147,7 @@ _TESTS_TO_SKIP_LEGACY = [
 ]
 
 _TESTS_TO_SKIP_PLANNER = [
- # TODO: Add strings.format and strings.quote.
- "string_ext/quote",
+ # TODO: Add strings.format.
  "string_ext/format",
  "string_ext/format_errors",
 

extensions/src/main/java/dev/cel/extensions/CelStringExtensions.java

@@ -137,6 +137,17 @@ public enum Function {
  SimpleType.STRING,
  SimpleType.STRING)),
  CelFunctionBinding.from("string_lower_ascii", String.class, Ascii::toLowerCase)),
+ QUOTE(
+ CelFunctionDecl.newFunctionDeclaration(
+ "strings.quote",
+ CelOverloadDecl.newGlobalOverload(
+ "strings_quote",
+ "Takes the given string and makes it safe to print (without any formatting"
+ + " due to escape sequences). If any invalid UTF-8 characters are"
+ + " encountered, they are replaced with \\uFFFD.",
+ SimpleType.STRING,
+ ImmutableList.of(SimpleType.STRING))),
+ CelFunctionBinding.from("strings_quote", String.class, CelStringExtensions::quote)),
  REPLACE(
  CelFunctionDecl.newFunctionDeclaration(
  "replace",
@@ -164,6 +175,16 @@ public enum Function {
  "string_replace_string_string_int",
  ImmutableList.of(String.class, String.class, String.class, Long.class),
  CelStringExtensions::replace)),
+ REVERSE(
+ CelFunctionDecl.newFunctionDeclaration(
+ "reverse",
+ CelOverloadDecl.newMemberOverload(
+ "string_reverse",
+ "Returns a new string whose characters are the same as the target string,"
+ + " only formatted in reverse order.",
+ SimpleType.STRING,
+ SimpleType.STRING)),
+ CelFunctionBinding.from("string_reverse", String.class, CelStringExtensions::reverse)),
  SPLIT(
  CelFunctionDecl.newFunctionDeclaration(
  "split",
@@ -449,6 +470,67 @@ private static Long lastIndexOf(CelCodePointArray str, CelCodePointArray substr,
  return -1L;
  }
 
+ private static String quote(String s) {
+ StringBuilder sb = new StringBuilder(s.length() + 2);
+ sb.append('"');
+ for (int i = 0; i < s.length(); ) {
+ int codePoint = s.codePointAt(i);
+ if (isMalformedUtf16(s, i, codePoint)) {
+ sb.append('\uFFFD');
+ i++;
+ continue;
+ }
+ switch (codePoint) {
+ case '\u0007':
+ sb.append("\\a");
+ break;
+ case '\b':
+ sb.append("\\b");
+ break;
+ case '\f':
+ sb.append("\\f");
+ break;
+ case '\n':
+ sb.append("\\n");
+ break;
+ case '\r':
+ sb.append("\\r");
+ break;
+ case '\t':
+ sb.append("\\t");
+ break;
+ case '\u000B':
+ sb.append("\\v");
+ break;
+ case '\\':
+ sb.append("\\\\");
+ break;
+ case '"':
+ sb.append("\\\"");
+ break;
+ default:
+ sb.appendCodePoint(codePoint);
+ break;
+ }
+ i += Character.charCount(codePoint);
+ }
+ sb.append('"');
+ return sb.toString();
+ }
+
+ private static boolean isMalformedUtf16(String s, int index, int codePoint) {
+ char currentChar = s.charAt(index);
+ if (!Character.isValidCodePoint(codePoint)) {
+ return true;
+ }
+ if (Character.isLowSurrogate(currentChar)) {
+ return true;
+ }
+ // Check for unpaired high surrogate
+ return Character.isHighSurrogate(currentChar)
+ && (index + 1 >= s.length() || !Character.isLowSurrogate(s.charAt(index + 1)));
+ }
+
  private static String replaceAll(Object[] objects) {
  return replace((String) objects[0], (String) objects[1], (String) objects[2], -1);
  }
@@ -504,6 +586,10 @@ private static String replace(String text, String searchString, String replaceme
  return sb.append(textCpa.slice(start, textCpa.length())).toString();
  }
 
+ private static String reverse(String s) {
+ return new StringBuilder(s).reverse().toString();
+ }
+
  private static List<String> split(String str, String separator) {
  return split(str, separator, Integer.MAX_VALUE);
  }

extensions/src/main/java/dev/cel/extensions/README.md

@@ -474,6 +474,19 @@ Examples:
  'TacoCat'.lowerAscii() // returns 'tacocat'
  'TacoCÆt Xii'.lowerAscii() // returns 'tacocÆt xii'
 
+### Quote
+
+Takes the given string and makes it safe to print (without any formatting due
+to escape sequences).
+If any invalid UTF-8 characters are encountered, they are replaced with \uFFFD.
+
+ strings.quote(<string>)
+
+Examples:
+
+ strings.quote('single-quote with "double quote"') // returns '"single-quote with \"double quote\""'
+ strings.quote("two escape sequences \a\n") // returns '"two escape sequences \\a\\n"'
+
 ### Replace
 
 Returns a new string based on the target, which replaces the occurrences of a
@@ -493,6 +506,20 @@ Examples:
  'hello hello'.replace('he', 'we', 1) // returns 'wello hello'
  'hello hello'.replace('he', 'we', 0) // returns 'hello hello'
 
+### Reverse
+
+Returns a new string whose characters are the same as the target string, only
+formatted in reverse order.
+This function relies on converting strings to Unicode code point arrays in
+order to reverse.
+
+ <string>.reverse() -> <string>
+
+Examples:
+
+ 'gums'.reverse() // returns 'smug'
+ 'John Smith'.reverse() // returns 'htimS nhoJ'
+
 ### Split
 
 Returns a mutable list of strings split from the input by the given separator. The

extensions/src/test/java/dev/cel/extensions/CelExtensionsTest.java

@@ -168,6 +168,7 @@ public void getAllFunctionNames() {
  "join",
  "lastIndexOf",
  "lowerAscii",
+ "strings.quote",
  "replace",
  "split",
  "substring",

extensions/src/test/java/dev/cel/extensions/CelStringExtensionsTest.java

@@ -33,6 +33,8 @@
 import dev.cel.runtime.CelEvaluationException;
 import dev.cel.runtime.CelRuntime;
 import dev.cel.runtime.CelRuntimeFactory;
+
+import java.nio.charset.StandardCharsets;
 import java.util.List;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -70,7 +72,9 @@ public void library() {
  "lastIndexOf",
  "lowerAscii",
  "replace",
+ "reverse",
  "split",
+ "strings.quote",
  "substring",
  "trim",
  "upperAscii");
@@ -1467,6 +1471,88 @@ public void stringExtension_functionSubset_success() throws Exception {
  assertThat(evaluatedResult).isEqualTo(true);
  }
 
+ @Test
+ @TestParameters("{string: 'abcd', expectedResult: 'dcba'}")
+ @TestParameters("{string: '', expectedResult: ''}")
+ @TestParameters("{string: 'a', expectedResult: 'a'}")
+ @TestParameters("{string: 'hello world', expectedResult: 'dlrow olleh'}")
+ @TestParameters("{string: 'ab가cd', expectedResult: 'dc가ba'}")
+ public void reverse_success(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("s.reverse()").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ @TestParameters("{string: '😁😑😦', expectedResult: '😦😑😁'}")
+ @TestParameters("{string: '\u180e\u200b\u200c\u200d\u2060\ufeff', expectedResult: '\ufeff\u2060\u200d\u200c\u200b\u180e'}")
+ public void reverse_unicode(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("s.reverse()").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ @TestParameters("{string: 'hello', expectedResult: '\"hello\"'}")
+ @TestParameters("{string: '', expectedResult: '\"\"'}")
+ @TestParameters("{string: 'contains \\\"quotes\\\"', expectedResult: '\"contains \\\\\\\"quotes\\\\\\\"\"'}")
+ @TestParameters("{string: 'ends with \\\\', expectedResult: '\"ends with \\\\\\\\\"'}")
+ @TestParameters("{string: '\\\\ starts with', expectedResult: '\"\\\\\\\\ starts with\"'}")
+ public void quote_success(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("strings.quote(s)").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ public void quote_singleWithDoubleQuotes() throws Exception {
+ String expr = "strings.quote('single-quote with \"double quote\"')";
+ String expected = "\"\\\"single-quote with \\\\\\\"double quote\\\\\\\"\\\"\"";
+ CelAbstractSyntaxTree ast = COMPILER.compile(expr + " == " + expected).getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval();
+
+ assertThat(evaluatedResult).isEqualTo(true);
+ }
+
+ @Test
+ public void quote_escapesSpecialCharacters() throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("strings.quote(s)").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult =
+ program.eval(
+ ImmutableMap.of(
+ "s", "\u0007bell\u000Bvtab\bback\ffeed\rret\nline\ttab\\slash 가 😁"));
+
+ assertThat(evaluatedResult)
+ .isEqualTo("\"\\abell\\vvtab\\bback\\ffeed\\rret\\nline\\ttab\\\\slash 가 😁\"");
+ }
+
+ @Test
+ public void quote_escapesMalformed_endWithHighSurrogate() throws Exception {
+ CelRuntime.Program program = RUNTIME.createProgram(COMPILER.compile("strings.quote(s)").getAst());
+ assertThat(program.eval(ImmutableMap.of("s", "end with high surrogate \uD83D")))
+ .isEqualTo("\"end with high surrogate \uFFFD\"");
+ }
+
+ @Test
+ public void quote_escapesMalformed_unpairedHighSurrogate() throws Exception {
+ CelRuntime.Program program = RUNTIME.createProgram(COMPILER.compile("strings.quote(s)").getAst());
+ assertThat(program.eval(ImmutableMap.of("s", "bad pair \uD83DA")))
+ .isEqualTo("\"bad pair \uFFFDA\"");
+ }
+
  @Test
  public void stringExtension_compileUnallowedFunction_throws() {
  CelCompiler celCompiler =

conformance/src/test/java/dev/cel/conformance/BUILD.bazel

@@ -119,8 +119,7 @@ _TESTS_TO_SKIP_LEGACY = [
 
  # Skip until fixed.
  "fields/qualified_identifier_resolution/map_value_repeat_key_heterogeneous",
- # TODO: Add strings.format and strings.quote.
- "string_ext/quote",
+ # TODO: Add strings.format.
  "string_ext/format",
  "string_ext/format_errors",
 
@@ -148,8 +147,7 @@ _TESTS_TO_SKIP_LEGACY = [
 ]
 
 _TESTS_TO_SKIP_PLANNER = [
- # TODO: Add strings.format and strings.quote.
- "string_ext/quote",
+ # TODO: Add strings.format.
  "string_ext/format",
  "string_ext/format_errors",
 

extensions/src/main/java/dev/cel/extensions/CelStringExtensions.java

@@ -137,6 +137,17 @@ public enum Function {
  SimpleType.STRING,
  SimpleType.STRING)),
  CelFunctionBinding.from("string_lower_ascii", String.class, Ascii::toLowerCase)),
+ QUOTE(
+ CelFunctionDecl.newFunctionDeclaration(
+ "strings.quote",
+ CelOverloadDecl.newGlobalOverload(
+ "strings_quote",
+ "Takes the given string and makes it safe to print (without any formatting"
+ + " due to escape sequences). If any invalid UTF-8 characters are"
+ + " encountered, they are replaced with \\uFFFD.",
+ SimpleType.STRING,
+ ImmutableList.of(SimpleType.STRING))),
+ CelFunctionBinding.from("strings_quote", String.class, CelStringExtensions::quote)),
  REPLACE(
  CelFunctionDecl.newFunctionDeclaration(
  "replace",
@@ -164,6 +175,16 @@ public enum Function {
  "string_replace_string_string_int",
  ImmutableList.of(String.class, String.class, String.class, Long.class),
  CelStringExtensions::replace)),
+ REVERSE(
+ CelFunctionDecl.newFunctionDeclaration(
+ "reverse",
+ CelOverloadDecl.newMemberOverload(
+ "string_reverse",
+ "Returns a new string whose characters are the same as the target string,"
+ + " only formatted in reverse order.",
+ SimpleType.STRING,
+ SimpleType.STRING)),
+ CelFunctionBinding.from("string_reverse", String.class, CelStringExtensions::reverse)),
  SPLIT(
  CelFunctionDecl.newFunctionDeclaration(
  "split",
@@ -449,6 +470,67 @@ private static Long lastIndexOf(CelCodePointArray str, CelCodePointArray substr,
  return -1L;
  }
 
+ private static String quote(String s) {
+ StringBuilder sb = new StringBuilder(s.length() + 2);
+ sb.append('"');
+ for (int i = 0; i < s.length(); ) {
+ int codePoint = s.codePointAt(i);
+ if (isMalformedUtf16(s, i, codePoint)) {
+ sb.append('\uFFFD');
+ i++;
+ continue;
+ }
+ switch (codePoint) {
+ case '\u0007':
+ sb.append("\\a");
+ break;
+ case '\b':
+ sb.append("\\b");
+ break;
+ case '\f':
+ sb.append("\\f");
+ break;
+ case '\n':
+ sb.append("\\n");
+ break;
+ case '\r':
+ sb.append("\\r");
+ break;
+ case '\t':
+ sb.append("\\t");
+ break;
+ case '\u000B':
+ sb.append("\\v");
+ break;
+ case '\\':
+ sb.append("\\\\");
+ break;
+ case '"':
+ sb.append("\\\"");
+ break;
+ default:
+ sb.appendCodePoint(codePoint);
+ break;
+ }
+ i += Character.charCount(codePoint);
+ }
+ sb.append('"');
+ return sb.toString();
+ }
+
+ private static boolean isMalformedUtf16(String s, int index, int codePoint) {
+ char currentChar = s.charAt(index);
+ if (!Character.isValidCodePoint(codePoint)) {
+ return true;
+ }
+ if (Character.isLowSurrogate(currentChar)) {
+ return true;
+ }
+ // Check for unpaired high surrogate
+ return Character.isHighSurrogate(currentChar)
+ && (index + 1 >= s.length() || !Character.isLowSurrogate(s.charAt(index + 1)));
+ }
+
  private static String replaceAll(Object[] objects) {
  return replace((String) objects[0], (String) objects[1], (String) objects[2], -1);
  }
@@ -504,6 +586,10 @@ private static String replace(String text, String searchString, String replaceme
  return sb.append(textCpa.slice(start, textCpa.length())).toString();
  }
 
+ private static String reverse(String s) {
+ return new StringBuilder(s).reverse().toString();
+ }
+
  private static List<String> split(String str, String separator) {
  return split(str, separator, Integer.MAX_VALUE);
  }

extensions/src/main/java/dev/cel/extensions/README.md

@@ -474,6 +474,19 @@ Examples:
  'TacoCat'.lowerAscii() // returns 'tacocat'
  'TacoCÆt Xii'.lowerAscii() // returns 'tacocÆt xii'
 
+### Quote
+
+Takes the given string and makes it safe to print (without any formatting due
+to escape sequences).
+If any invalid UTF-8 characters are encountered, they are replaced with \uFFFD.
+
+ strings.quote(<string>)
+
+Examples:
+
+ strings.quote('single-quote with "double quote"') // returns '"single-quote with \"double quote\""'
+ strings.quote("two escape sequences \a\n") // returns '"two escape sequences \\a\\n"'
+
 ### Replace
 
 Returns a new string based on the target, which replaces the occurrences of a
@@ -493,6 +506,20 @@ Examples:
  'hello hello'.replace('he', 'we', 1) // returns 'wello hello'
  'hello hello'.replace('he', 'we', 0) // returns 'hello hello'
 
+### Reverse
+
+Returns a new string whose characters are the same as the target string, only
+formatted in reverse order.
+This function relies on converting strings to Unicode code point arrays in
+order to reverse.
+
+ <string>.reverse() -> <string>
+
+Examples:
+
+ 'gums'.reverse() // returns 'smug'
+ 'John Smith'.reverse() // returns 'htimS nhoJ'
+
 ### Split
 
 Returns a mutable list of strings split from the input by the given separator. The

extensions/src/test/java/dev/cel/extensions/CelExtensionsTest.java

@@ -168,6 +168,7 @@ public void getAllFunctionNames() {
  "join",
  "lastIndexOf",
  "lowerAscii",
+ "strings.quote",
  "replace",
  "split",
  "substring",

extensions/src/test/java/dev/cel/extensions/CelStringExtensionsTest.java

@@ -33,6 +33,8 @@
 import dev.cel.runtime.CelEvaluationException;
 import dev.cel.runtime.CelRuntime;
 import dev.cel.runtime.CelRuntimeFactory;
+
+import java.nio.charset.StandardCharsets;
 import java.util.List;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -70,7 +72,9 @@ public void library() {
  "lastIndexOf",
  "lowerAscii",
  "replace",
+ "reverse",
  "split",
+ "strings.quote",
  "substring",
  "trim",
  "upperAscii");
@@ -1467,6 +1471,88 @@ public void stringExtension_functionSubset_success() throws Exception {
  assertThat(evaluatedResult).isEqualTo(true);
  }
 
+ @Test
+ @TestParameters("{string: 'abcd', expectedResult: 'dcba'}")
+ @TestParameters("{string: '', expectedResult: ''}")
+ @TestParameters("{string: 'a', expectedResult: 'a'}")
+ @TestParameters("{string: 'hello world', expectedResult: 'dlrow olleh'}")
+ @TestParameters("{string: 'ab가cd', expectedResult: 'dc가ba'}")
+ public void reverse_success(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("s.reverse()").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ @TestParameters("{string: '😁😑😦', expectedResult: '😦😑😁'}")
+ @TestParameters("{string: '\u180e\u200b\u200c\u200d\u2060\ufeff', expectedResult: '\ufeff\u2060\u200d\u200c\u200b\u180e'}")
+ public void reverse_unicode(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("s.reverse()").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ @TestParameters("{string: 'hello', expectedResult: '\"hello\"'}")
+ @TestParameters("{string: '', expectedResult: '\"\"'}")
+ @TestParameters("{string: 'contains \\\"quotes\\\"', expectedResult: '\"contains \\\\\\\"quotes\\\\\\\"\"'}")
+ @TestParameters("{string: 'ends with \\\\', expectedResult: '\"ends with \\\\\\\\\"'}")
+ @TestParameters("{string: '\\\\ starts with', expectedResult: '\"\\\\\\\\ starts with\"'}")
+ public void quote_success(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("strings.quote(s)").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ public void quote_singleWithDoubleQuotes() throws Exception {
+ String expr = "strings.quote('single-quote with \"double quote\"')";
+ String expected = "\"\\\"single-quote with \\\\\\\"double quote\\\\\\\"\\\"\"";
+ CelAbstractSyntaxTree ast = COMPILER.compile(expr + " == " + expected).getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval();
+
+ assertThat(evaluatedResult).isEqualTo(true);
+ }
+
+ @Test
+ public void quote_escapesSpecialCharacters() throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("strings.quote(s)").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult =
+ program.eval(
+ ImmutableMap.of(
+ "s", "\u0007bell\u000Bvtab\bback\ffeed\rret\nline\ttab\\slash 가 😁"));
+
+ assertThat(evaluatedResult)
+ .isEqualTo("\"\\abell\\vvtab\\bback\\ffeed\\rret\\nline\\ttab\\\\slash 가 😁\"");
+ }
+
+ @Test
+ public void quote_escapesMalformed_endWithHighSurrogate() throws Exception {
+ CelRuntime.Program program = RUNTIME.createProgram(COMPILER.compile("strings.quote(s)").getAst());
+ assertThat(program.eval(ImmutableMap.of("s", "end with high surrogate \uD83D")))
+ .isEqualTo("\"end with high surrogate \uFFFD\"");
+ }
+
+ @Test
+ public void quote_escapesMalformed_unpairedHighSurrogate() throws Exception {
+ CelRuntime.Program program = RUNTIME.createProgram(COMPILER.compile("strings.quote(s)").getAst());
+ assertThat(program.eval(ImmutableMap.of("s", "bad pair \uD83DA")))
+ .isEqualTo("\"bad pair \uFFFDA\"");
+ }
+
  @Test
  public void stringExtension_compileUnallowedFunction_throws() {
  CelCompiler celCompiler =

conformance/src/test/java/dev/cel/conformance/BUILD.bazel

@@ -119,8 +119,7 @@ _TESTS_TO_SKIP_LEGACY = [
 
  # Skip until fixed.
  "fields/qualified_identifier_resolution/map_value_repeat_key_heterogeneous",
- # TODO: Add strings.format and strings.quote.
- "string_ext/quote",
+ # TODO: Add strings.format.
  "string_ext/format",
  "string_ext/format_errors",
 
@@ -148,8 +147,7 @@ _TESTS_TO_SKIP_LEGACY = [
 ]
 
 _TESTS_TO_SKIP_PLANNER = [
- # TODO: Add strings.format and strings.quote.
- "string_ext/quote",
+ # TODO: Add strings.format.
  "string_ext/format",
  "string_ext/format_errors",
 

extensions/src/main/java/dev/cel/extensions/CelStringExtensions.java

@@ -137,6 +137,17 @@ public enum Function {
  SimpleType.STRING,
  SimpleType.STRING)),
  CelFunctionBinding.from("string_lower_ascii", String.class, Ascii::toLowerCase)),
+ QUOTE(
+ CelFunctionDecl.newFunctionDeclaration(
+ "strings.quote",
+ CelOverloadDecl.newGlobalOverload(
+ "strings_quote",
+ "Takes the given string and makes it safe to print (without any formatting"
+ + " due to escape sequences). If any invalid UTF-8 characters are"
+ + " encountered, they are replaced with \\uFFFD.",
+ SimpleType.STRING,
+ ImmutableList.of(SimpleType.STRING))),
+ CelFunctionBinding.from("strings_quote", String.class, CelStringExtensions::quote)),
  REPLACE(
  CelFunctionDecl.newFunctionDeclaration(
  "replace",
@@ -164,6 +175,16 @@ public enum Function {
  "string_replace_string_string_int",
  ImmutableList.of(String.class, String.class, String.class, Long.class),
  CelStringExtensions::replace)),
+ REVERSE(
+ CelFunctionDecl.newFunctionDeclaration(
+ "reverse",
+ CelOverloadDecl.newMemberOverload(
+ "string_reverse",
+ "Returns a new string whose characters are the same as the target string,"
+ + " only formatted in reverse order.",
+ SimpleType.STRING,
+ SimpleType.STRING)),
+ CelFunctionBinding.from("string_reverse", String.class, CelStringExtensions::reverse)),
  SPLIT(
  CelFunctionDecl.newFunctionDeclaration(
  "split",
@@ -449,6 +470,67 @@ private static Long lastIndexOf(CelCodePointArray str, CelCodePointArray substr,
  return -1L;
  }
 
+ private static String quote(String s) {
+ StringBuilder sb = new StringBuilder(s.length() + 2);
+ sb.append('"');
+ for (int i = 0; i < s.length(); ) {
+ int codePoint = s.codePointAt(i);
+ if (isMalformedUtf16(s, i, codePoint)) {
+ sb.append('\uFFFD');
+ i++;
+ continue;
+ }
+ switch (codePoint) {
+ case '\u0007':
+ sb.append("\\a");
+ break;
+ case '\b':
+ sb.append("\\b");
+ break;
+ case '\f':
+ sb.append("\\f");
+ break;
+ case '\n':
+ sb.append("\\n");
+ break;
+ case '\r':
+ sb.append("\\r");
+ break;
+ case '\t':
+ sb.append("\\t");
+ break;
+ case '\u000B':
+ sb.append("\\v");
+ break;
+ case '\\':
+ sb.append("\\\\");
+ break;
+ case '"':
+ sb.append("\\\"");
+ break;
+ default:
+ sb.appendCodePoint(codePoint);
+ break;
+ }
+ i += Character.charCount(codePoint);
+ }
+ sb.append('"');
+ return sb.toString();
+ }
+
+ private static boolean isMalformedUtf16(String s, int index, int codePoint) {
+ char currentChar = s.charAt(index);
+ if (!Character.isValidCodePoint(codePoint)) {
+ return true;
+ }
+ if (Character.isLowSurrogate(currentChar)) {
+ return true;
+ }
+ // Check for unpaired high surrogate
+ return Character.isHighSurrogate(currentChar)
+ && (index + 1 >= s.length() || !Character.isLowSurrogate(s.charAt(index + 1)));
+ }
+
  private static String replaceAll(Object[] objects) {
  return replace((String) objects[0], (String) objects[1], (String) objects[2], -1);
  }
@@ -504,6 +586,10 @@ private static String replace(String text, String searchString, String replaceme
  return sb.append(textCpa.slice(start, textCpa.length())).toString();
  }
 
+ private static String reverse(String s) {
+ return new StringBuilder(s).reverse().toString();
+ }
+
  private static List<String> split(String str, String separator) {
  return split(str, separator, Integer.MAX_VALUE);
  }

extensions/src/main/java/dev/cel/extensions/README.md

@@ -474,6 +474,19 @@ Examples:
  'TacoCat'.lowerAscii() // returns 'tacocat'
  'TacoCÆt Xii'.lowerAscii() // returns 'tacocÆt xii'
 
+### Quote
+
+Takes the given string and makes it safe to print (without any formatting due
+to escape sequences).
+If any invalid UTF-8 characters are encountered, they are replaced with \uFFFD.
+
+ strings.quote(<string>)
+
+Examples:
+
+ strings.quote('single-quote with "double quote"') // returns '"single-quote with \"double quote\""'
+ strings.quote("two escape sequences \a\n") // returns '"two escape sequences \\a\\n"'
+
 ### Replace
 
 Returns a new string based on the target, which replaces the occurrences of a
@@ -493,6 +506,20 @@ Examples:
  'hello hello'.replace('he', 'we', 1) // returns 'wello hello'
  'hello hello'.replace('he', 'we', 0) // returns 'hello hello'
 
+### Reverse
+
+Returns a new string whose characters are the same as the target string, only
+formatted in reverse order.
+This function relies on converting strings to Unicode code point arrays in
+order to reverse.
+
+ <string>.reverse() -> <string>
+
+Examples:
+
+ 'gums'.reverse() // returns 'smug'
+ 'John Smith'.reverse() // returns 'htimS nhoJ'
+
 ### Split
 
 Returns a mutable list of strings split from the input by the given separator. The

extensions/src/test/java/dev/cel/extensions/CelExtensionsTest.java

@@ -168,6 +168,7 @@ public void getAllFunctionNames() {
  "join",
  "lastIndexOf",
  "lowerAscii",
+ "strings.quote",
  "replace",
  "split",
  "substring",

extensions/src/test/java/dev/cel/extensions/CelStringExtensionsTest.java

@@ -33,6 +33,8 @@
 import dev.cel.runtime.CelEvaluationException;
 import dev.cel.runtime.CelRuntime;
 import dev.cel.runtime.CelRuntimeFactory;
+
+import java.nio.charset.StandardCharsets;
 import java.util.List;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -70,7 +72,9 @@ public void library() {
  "lastIndexOf",
  "lowerAscii",
  "replace",
+ "reverse",
  "split",
+ "strings.quote",
  "substring",
  "trim",
  "upperAscii");
@@ -1467,6 +1471,88 @@ public void stringExtension_functionSubset_success() throws Exception {
  assertThat(evaluatedResult).isEqualTo(true);
  }
 
+ @Test
+ @TestParameters("{string: 'abcd', expectedResult: 'dcba'}")
+ @TestParameters("{string: '', expectedResult: ''}")
+ @TestParameters("{string: 'a', expectedResult: 'a'}")
+ @TestParameters("{string: 'hello world', expectedResult: 'dlrow olleh'}")
+ @TestParameters("{string: 'ab가cd', expectedResult: 'dc가ba'}")
+ public void reverse_success(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("s.reverse()").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ @TestParameters("{string: '😁😑😦', expectedResult: '😦😑😁'}")
+ @TestParameters("{string: '\u180e\u200b\u200c\u200d\u2060\ufeff', expectedResult: '\ufeff\u2060\u200d\u200c\u200b\u180e'}")
+ public void reverse_unicode(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("s.reverse()").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ @TestParameters("{string: 'hello', expectedResult: '\"hello\"'}")
+ @TestParameters("{string: '', expectedResult: '\"\"'}")
+ @TestParameters("{string: 'contains \\\"quotes\\\"', expectedResult: '\"contains \\\\\\\"quotes\\\\\\\"\"'}")
+ @TestParameters("{string: 'ends with \\\\', expectedResult: '\"ends with \\\\\\\\\"'}")
+ @TestParameters("{string: '\\\\ starts with', expectedResult: '\"\\\\\\\\ starts with\"'}")
+ public void quote_success(String string, String expectedResult) throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("strings.quote(s)").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval(ImmutableMap.of("s", string));
+
+ assertThat(evaluatedResult).isEqualTo(expectedResult);
+ }
+
+ @Test
+ public void quote_singleWithDoubleQuotes() throws Exception {
+ String expr = "strings.quote('single-quote with \"double quote\"')";
+ String expected = "\"\\\"single-quote with \\\\\\\"double quote\\\\\\\"\\\"\"";
+ CelAbstractSyntaxTree ast = COMPILER.compile(expr + " == " + expected).getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult = program.eval();
+
+ assertThat(evaluatedResult).isEqualTo(true);
+ }
+
+ @Test
+ public void quote_escapesSpecialCharacters() throws Exception {
+ CelAbstractSyntaxTree ast = COMPILER.compile("strings.quote(s)").getAst();
+ CelRuntime.Program program = RUNTIME.createProgram(ast);
+
+ Object evaluatedResult =
+ program.eval(
+ ImmutableMap.of(
+ "s", "\u0007bell\u000Bvtab\bback\ffeed\rret\nline\ttab\\slash 가 😁"));
+
+ assertThat(evaluatedResult)
+ .isEqualTo("\"\\abell\\vvtab\\bback\\ffeed\\rret\\nline\\ttab\\\\slash 가 😁\"");
+ }
+
+ @Test
+ public void quote_escapesMalformed_endWithHighSurrogate() throws Exception {
+ CelRuntime.Program program = RUNTIME.createProgram(COMPILER.compile("strings.quote(s)").getAst());
+ assertThat(program.eval(ImmutableMap.of("s", "end with high surrogate \uD83D")))
+ .isEqualTo("\"end with high surrogate \uFFFD\"");
+ }
+
+ @Test
+ public void quote_escapesMalformed_unpairedHighSurrogate() throws Exception {
+ CelRuntime.Program program = RUNTIME.createProgram(COMPILER.compile("strings.quote(s)").getAst());
+ assertThat(program.eval(ImmutableMap.of("s", "bad pair \uD83DA")))
+ .isEqualTo("\"bad pair \uFFFDA\"");
+ }
+
  @Test
  public void stringExtension_compileUnallowedFunction_throws() {
  CelCompiler celCompiler =