cpp_restore/parser.cpp at master · doomsday/cpp_restore · GitHub

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#include"parser_impl.hpp"
#include"table.hpp"

doubleParser::prim(bool get){

using Lexer::number_value;
using Lexer::string_value;
if(get) get_token();
switch (curr_tok) {
caseNUMBER: // Floating-point constant
 {
double v = number_value;
get_token();
return v;
 }
caseNAME:
 {
double& v = table[string_value];
if(Lexer::get_token() == ASSIGN) v = expr(true);
return v;
 }
caseMINUS: // Unary minus
return -prim(true);
caseLP:
 {
double e = expr(true);
if (curr_tok != RP) throwSyntax_error(") expected");
get_token(); // Eat ')'
return e;
 }
default:
throwSyntax_error("primary expected");
 }
}

doubleParser::term(bool get) {
double left = prim(get);
for(;;)
switch (curr_tok) {
caseMUL:
 left *= prim(true);
break;
caseDIV:
if (double d = prim(true)) {
 left /= d;
break;
 }
throwZero_divide();
default:
return left;
 }
}

doubleParser::expr(bool get) {
double left = term(get);
for(;;)
switch (curr_tok) {
casePLUS:
 left += term(true);
break;
caseMINUS:
 left -= term(true);
break;
default:
return left;
 }
}