Negative parsing fix #115
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Negative parsing fix #115
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Can we make sure that all these tests pass? test.equal(expr('a * - b').collapse().toString(), 'a × (−b)'); // works!
test.equal(expr('a + - b').collapse().toString(), 'a + (−b)');
test.equal(expr('a - - b').collapse().toString(), 'a − (−b)');
test.equal(expr('10% - b').collapse().toString(), '10% − b');
test.equal(expr('-(a + b)').collapse().toString(), '−(a + b)'); // works!
test.throws(() => expr('a - - - b')); |
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If |
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Sure, we can do that too! |
pjhenning
reviewed
Nov 21, 2023
src/parser.ts
Outdated
| @@ -163,6 +163,22 @@ function findBinaryFunction(tokens: ExprElement[], fn: string) { | |||
| } | |||
| } | |||
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| // Some minuses have been parsed as functions (i.e. an `ExprFunction` with a single argument). | |||
| // If they are preceded by something, we need to treat the expression as a unary minus. | |||
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Hello, what do you think about rephrasing this comment to something like this:
// Some minuses are initially parsed as unary functions (i.e. the string "- b" is parsed an `ExprFunction` with
// `.fn` = "−" and an `ExprIdentifier` "b" as its single argument.)
// If any unary minus function is preceded by another token, we need to merge the pair of tokens into a binary minus
// function.
pjhenning
approved these changes
Nov 21, 2023
pjhenning
reviewed
Nov 29, 2023
src/parser.ts
Outdated
| tokens.splice(0, 2, new ExprFunction((tokens[0] as ExprOperator).o, [tokens[1]])); | ||
| } | ||
| findBinaryFunction(tokens, '− ±'); | ||
| findBinaryFunction(tokens, '- −'); |
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I don't think it should be a part of this PR but perhaps some day we should rename this function and findBinaryMinusFunctions to have more descriptive names, and/or add a doc comment to the former. To help distinguish what they do.
swarty
reviewed
Dec 22, 2023
src/parser.ts
Outdated
Comment on lines
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| function findBinaryMinusFunctions(tokens: ExprElement[]) { | ||
| for (let i = 1; i < tokens.length; i++) { | ||
| const token = tokens[i]; | ||
| if (token instanceof ExprFunction && token.fn === '−') { | ||
| const a = tokens[i - 1]; | ||
| const b = token.args[0]; | ||
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| const args = [removeBrackets(a), removeBrackets(b)]; | ||
| tokens.splice(i - 1, 2, new ExprFunction('−', args)); | ||
| i -= 1; | ||
| } | ||
| } | ||
| } |
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i can not understand this function, this is not return and do not modify anything except function param, just loop?
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- looks like it should return tokens as result or throw some error as in
findBinaryFunctionfunction? - redeclaring/modifying function param makes code readability so hard.
swarty
approved these changes
Jan 16, 2024
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Fixes parsing problems with consecutive operators, where one operator is a '-'. This led to expressions such as '2 x -3' being invalid.