Arithmetic Evaluator/Go: Difference between revisions

__TOC__

=Operator precedence parser=

This is an operator precedence parser. The number format used in calculation can be changed with the line "type Number int".

 

 

import (

}

}

 

Example

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=Library=

Shown here is use of the package go/parser in the standard library. For the Go 1 release, there is a parser in the standard library, but not an evaluator. Evaluation is relatively easy though, once you have a parse tree.

"go", // a valid keyword, not valid in an expression.

"3@7", // error message is "illegal character."

"", // EOF seems a reasonable error message.

}

 

func parseAndEval(exp string) (int, error) {

if err != nil {

return 0, err

go: 1:1: expected operand, found 'go'

3@7: 1:2: illegal character U+0040 '@'

: 1:1: expected operand, found 'EOF'

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