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Change +, -, *, /, //, and % operators' associativity to left-to-right #280

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Change +, -, *, /, //, and % operators' associativity to left-to-right #280

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03f165c
Change + - * / // % operators' associativity to left-to-right
6aJIaJIae4HuK Aug 10, 2025
a647280
Minor fix (now '2+' is error)
6aJIaJIae4HuK Aug 10, 2025
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107 changes: 55 additions & 52 deletions src/expression_parser.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -196,64 +196,67 @@ ExpressionParser::ParseResult<ExpressionEvaluatorPtr<Expression>> ExpressionPars

ExpressionParser::ParseResult<ExpressionEvaluatorPtr<Expression>> ExpressionParser::ParseMathPlusMinus(LexScanner& lexer)
{
auto left = ParseMathMulDiv(lexer);
if (!left)
return left;

auto tok = lexer.NextToken();
BinaryExpression::Operation operation;
switch (tok.type)
{
case '+':
operation = BinaryExpression::Plus;
break;
case '-':
operation = BinaryExpression::Minus;
break;
default:
lexer.ReturnToken();
return left;
auto res = ParseMathMulDiv(lexer);
if (!res)
return res;

while (true) {
auto tok = lexer.NextToken();
BinaryExpression::Operation operation;
switch (tok.type)
{
case '+':
operation = BinaryExpression::Plus;
break;
case '-':
operation = BinaryExpression::Minus;
break;
default:
lexer.ReturnToken();
return res;
}
auto right = ParseMathMulDiv(lexer);
if (!right)
return right;
res = std::make_shared<BinaryExpression>(operation, *res, *right);
}

auto right = ParseMathPlusMinus(lexer);
if (!right)
return right;

return std::make_shared<BinaryExpression>(operation, *left, *right);
return res;
}

ExpressionParser::ParseResult<ExpressionEvaluatorPtr<Expression>> ExpressionParser::ParseMathMulDiv(LexScanner& lexer)
{
auto left = ParseUnaryPlusMinus(lexer);
if (!left)
return left;

auto tok = lexer.NextToken();
BinaryExpression::Operation operation;
switch (tok.type)
{
case '*':
operation = BinaryExpression::Mul;
break;
case '/':
operation = BinaryExpression::Div;
break;
case Token::DivDiv:
operation = BinaryExpression::DivInteger;
break;
case '%':
operation = BinaryExpression::DivRemainder;
break;
default:
lexer.ReturnToken();
return left;
auto res = ParseUnaryPlusMinus(lexer);
if (!res)
return res;

while (true) {
auto tok = lexer.NextToken();
BinaryExpression::Operation operation;
switch (tok.type)
{
case '*':
operation = BinaryExpression::Mul;
break;
case '/':
operation = BinaryExpression::Div;
break;
case Token::DivDiv:
operation = BinaryExpression::DivInteger;
break;
case '%':
operation = BinaryExpression::DivRemainder;
break;
default:
lexer.ReturnToken();
return res;
}
auto right = ParseUnaryPlusMinus(lexer);
if (!right)
return right;
res = std::make_shared<BinaryExpression>(operation, *res, *right);
}

auto right = ParseMathMulDiv(lexer);
if (!right)
return right;

return std::make_shared<BinaryExpression>(operation, *left, *right);

return res;
}

ExpressionParser::ParseResult<ExpressionEvaluatorPtr<Expression>> ExpressionParser::ParseUnaryPlusMinus(LexScanner& lexer)
Expand Down
4 changes: 4 additions & 0 deletions test/expressions_test.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,8 @@ R"(
{{ 3 ** 4 }}
{{ 10 ** -2 }}
{{ 10/10 + 2*5 }}
{{ 10 - 2 - 4 }}
{{ 200 / 2 / 2 }}
{{ ([1, 2] + [3, 4]) | pprint }}
{{ 'Hello' + " " + 'World ' + stringValue }}
{{ 'Hello' + " " + 'World ' + wstringValue }}
Expand Down Expand Up @@ -53,6 +55,8 @@ R"(
81
0.01
11
4
50
[1, 2, 3, 4]
Hello World rain
Hello World rain
Expand Down