oec/goparsify
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Update readme

Browse Source
This commit is contained in:
Adam Scarr 2017-08-09 21:26:27 +10:00
parent 47badae641
commit d4b58316bc
1 changed files with 4 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
readme.md
View File

@ -1,10 +1,9 @@
goparsify [![CircleCI](https://circleci.com/gh/Vektah/goparsify/tree/master.svg?style=shield)](https://circleci.com/gh/Vektah/goparsify/tree/master) [![godoc](http://b.repl.ca/v1/godoc-wip-lightgrey.png)](https://godoc.org/github.com/Vektah/goparsify) goparsify [![CircleCI](https://circleci.com/gh/Vektah/goparsify/tree/master.svg?style=shield)](https://circleci.com/gh/Vektah/goparsify/tree/master) [![godoc](http://b.repl.ca/v1/godoc-reference-blue.png)](https://godoc.org/github.com/Vektah/goparsify)
========= =========
A parser-combinator library for building easy to test, read and maintain parsers using functional composition. A parser-combinator library for building easy to test, read and maintain parsers using functional composition.
### todo ### todo
- godoc: I've been slack and the interfaces have been changing rapidly.
- fatal errors: Some way for a parser to say "Ive found a good match, the input is broken, stop here with an error" - fatal errors: Some way for a parser to say "Ive found a good match, the input is broken, stop here with an error"
- better errors: currently only the longest error is returned, but it would be nice to show all expected tokens that could follow. - better errors: currently only the longest error is returned, but it would be nice to show all expected tokens that could follow.
@ -76,18 +75,14 @@ var number = Map(NumberLit(), func(n Node) Node {
}) })
func Calc(input string) (float64, error) { func Calc(input string) (float64, error) {
result, remaining, err := ParseString(number, input) result, err := Run(y, input)
if err != nil { if err != nil {
return 0, err return 0, err
} }
if remaining != "" {
return result.(float64), errors.New("left unparsed: " + remaining)
}
return result.(float64), nil return result.(float64), nil
} }
``` ```
This parser will return numbers either as float64 or int depending on the literal, for this calculator we only want floats so we Map the results and type cast. This parser will return numbers either as float64 or int depending on the literal, for this calculator we only want floats so we Map the results and type cast.
@ -121,7 +116,7 @@ sum = Map(Seq(number, Some(And(sumOp, number))), func(n Node) Node {
return Node{Result: i} return Node{Result: i}
}) })
// and update Calc to point to the new root parser -> `result, remaining, err := ParseString(sum, input)` // and update Calc to point to the new root parser -> `result, err := ParseString(sum, input)`
``` ```
This parser will match number ([+-] number)+, then map its to be the sum. See how the Child map directly to the positions in the parsers? n is the result of the and, `n.Child[0]` is its first argument, `n.Child[1]` is the result of the Some parser, `n.Child[1].Child[0]` is the result of the first And and so fourth. Given how closely tied the parser and the Map are it is good to keep the two together. This parser will match number ([+-] number)+, then map its to be the sum. See how the Child map directly to the positions in the parsers? n is the result of the and, `n.Child[0]` is its first argument, `n.Child[1]` is the result of the Some parser, `n.Child[1].Child[0]` is the result of the first And and so fourth. Given how closely tied the parser and the Map are it is good to keep the two together.