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Adding split method to string class#60

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Merged
ncw merged 6 commits into from
May 28, 2019
Merged

Adding split method to string class #60

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a8debc6
Adding split method to string class
kellrott May 17, 2019
cd235f2
Adding test for str split method
kellrott May 17, 2019
d3c579d
Fixing .split exception and added more python tests
kellrott May 24, 2019
f7ab626
Closer matching to python string split behavior
kellrott May 24, 2019
2f4feef
Fixing error message so it matches one from python3.4
kellrott May 28, 2019
e316b2b
Fixing error message to match python3.4 (previous version was python3.7)
kellrott May 28, 2019
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68 changes: 68 additions & 0 deletions py/string.go
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Original file line numberDiff line numberDiff line change
Expand Up@@ -17,6 +17,7 @@ import (
"fmt"
"strconv"
"strings"
"unicode"
"unicode/utf8"
)

Expand All@@ -34,6 +35,73 @@ or repr(object).
encoding defaults to sys.getdefaultencoding().
errors defaults to 'strict'.`, StrNew, nil)

// standard golang strings.Fields doesn't have a 'first N' argument
func fieldsN(s string, n int) []string {
out := []string{}
cur := []rune{}
r := []rune(s)
for _, c := range r {
//until we have covered the first N elements, multiple white-spaces are 'merged'
if n < 0 || len(out) < n {
if unicode.IsSpace(c) {
if len(cur) > 0 {
out = append(out, string(cur))
cur = []rune{}
}
} else {
cur = append(cur, c)
}
//until we see the next letter, after collecting the first N fields, continue to merge whitespaces
} else if len(out) == n && len(cur) == 0 {
if !unicode.IsSpace(c) {
cur = append(cur, c)
}
//now that enough words have been collected, just copy into the last element
} else {
cur = append(cur, c)
}
}
if len(cur) > 0 {
out = append(out, string(cur))
}
return out
}

func init() {
StringType.Dict["split"] = MustNewMethod("split", func(self Object, args Tuple) (Object, error) {
selfStr := self.(String)
var value Object = None
zeroRemove := true
if len(args) > 0 {
if _, ok := args[0].(NoneType); !ok {
value = args[0]
zeroRemove = false
}
}
var maxSplit int = -2
if len(args) > 1 {
if m, ok := args[1].(Int); ok {
maxSplit = int(m)
}
}
valArray := []string{}
if valStr, ok := value.(String); ok {
valArray = strings.SplitN(string(selfStr), string(valStr), maxSplit+1)
} else if _, ok := value.(NoneType); ok {
valArray = fieldsN(string(selfStr), maxSplit)
} else {
return nil, ExceptionNewf(TypeError, "Can't convert '%s' object to str implicitly", value.Type())
}
o := List{}
for _, j := range valArray {
if len(j) > 0 || !zeroRemove {
o.Items = append(o.Items, String(j))
}
}
return &o, nil
}, 0, "split(sub) -> split string with sub.")

@ncwncwMay 18, 2019

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The Python help is

 S.split([sep [,maxsplit]]) -> list of strings
Return a list of the words in the string S, using sep as the
delimiter string. If maxsplit is given, at most maxsplit
splits are done. If sep is not specified or is None, any
whitespace string is a separator and empty strings are removed
from the result.

Which makes me see that we are missing two things.

  • If sep isn't passed (or is None) in then we should be using strings.Fields in go terms (This doesn't have a maxfields parameter though.)
  • There is another optional parameter to specify the number of splits.

Here are some cases to consider

>>> "a,d,c".split(",")
['a', 'd', 'c']
>>> "a,d,c".split(",",1)
['a', 'd,c']
>>> " a d b ".split()
['a', 'd', 'b']
>>> " a d b ".split(None, 1)
['a', 'd b ']

}

// Type of this object
func (s String) Type() *Type {
return StringType
Expand Down
8 changes: 8 additions & 0 deletions py/tests/string.py
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Original file line numberDiff line numberDiff line change
Expand Up@@ -99,6 +99,14 @@ class C():
asc="hello"
uni="£100世界𠜎" # 1,2,3,4 byte unicode characters

doc="split"
assert ["0","1","2","4"] == list("0,1,2,4".split(","))
assert [""] == list("".split(","))
assert ['a', 'd,c'] == list("a,d,c".split(",",1))
assert ['a', 'd', 'b'] == list(" a d b ".split())
assert ['a', 'd b '] == list(" a d b ".split(None, 1))
assertRaisesText(TypeError, "Can't convert 'int' object to str implicitly", lambda: "0,1,2,4".split(1))

doc="ascii len"
assert len(asc) == 5

Expand Down