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https://github.com/prataprc/goparsec
Parser combinator in Go. If there are any cross platform issues or backward compatibility issues, please reach out.
https://github.com/prataprc/goparsec
golang parsec parser parser-combinators parsercombinator
Last synced: about 2 months ago
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Parser combinator in Go. If there are any cross platform issues or backward compatibility issues, please reach out.
- Host: GitHub
- URL: https://github.com/prataprc/goparsec
- Owner: prataprc
- License: other
- Created: 2014-01-12T18:55:06.000Z (over 10 years ago)
- Default Branch: master
- Last Pushed: 2021-12-19T14:25:20.000Z (almost 3 years ago)
- Last Synced: 2024-07-04T22:58:07.710Z (3 months ago)
- Topics: golang, parsec, parser, parser-combinators, parsercombinator
- Language: Go
- Homepage: http://prataprc.github.io/astquery.io
- Size: 1.44 MB
- Stars: 276
- Watchers: 14
- Forks: 23
- Open Issues: 12
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-combinator-parsers - prataprc/goparsec
README
Parser combinator library in Golang
===================================
[](https://travis-ci.org/prataprc/goparsec)
[](https://coveralls.io/github/prataprc/goparsec?branch=master)
[](https://godoc.org/github.com/prataprc/goparsec)
[](https://sourcegraph.com/github.com/prataprc/goparsec?badge)
[](https://goreportcard.com/report/github.com/prataprc/goparsec)
A library to construct top-down recursive backtracking parsers using
parser-combinators. Before proceeding you might want to take at peep
at [theory of parser combinators][theory-link]. As for this package, it
provides:
* A standard set of combinators.
* [Regular expression][regexp-link] based simple-scanner.
* Standard set of tokenizers based on the simple-scanner.
To construct syntax-trees based on detailed grammar try with
[AST struct][ast-link]
* Standard set of combinators are exported as methods to AST.
* Generate dot-graph EG: [dotfile](testdata/simple.dot)
for [html](testdata/simple.html).
* Pretty print on the console.
* Make debugging easier.
**NOTE that AST object is a recent development and expect user to adapt to
newer versions**
Quick links
-----------
* [Go documentation][goparsec-godoc-link].
* [Using the builtin scanner](#using-the-builtin-scanner).
* [Simple HTML parser][htmlparsec-link].
* [Querying Abstract Syntax Tree][astquery-link]
* [Projects using goparsec](#projects-using-goparsec).
* [Articles](#articles).
* [How to contribute](#how-to-contribute).
Combinators
-----------
Every combinator should confirm to the following signature,
```go
// ParsecNode type defines a node in the AST
type ParsecNode interface{}
// Parser function parses input text, higher order parsers are
// constructed using combinators.
type Parser func(Scanner) (ParsecNode, Scanner)
// Nodify callback function to construct custom ParsecNode.
type Nodify func([]ParsecNode) ParsecNode
```
Combinators take a variable number of parser functions and
return a new parser function.
Using the builtin scanner
-------------------------
Builtin scanner library manages the input buffer and implements a cursor
into the buffer. Create a new scanner instance,
```go
s := parsec.NewScanner(text)
```
The scanner library supplies method like ``Match(pattern)``,
``SkipAny(pattern)`` and ``Endof()``, [refer][goparsec-godoc-link] to for
more information on each of these methods.
Panics and Recovery
-------------------
Panics are to be expected when APIs are misused. Programmers might choose
to ignore errors, but not panics. For example:
* Kleene and Many combinators take one or two parsers as arguments. Less than
one or more than two will throw a panic.
* ManyUntil combinator take two or three parsers as arguments. Less than two
or more than three will throw a panic.
* Combinators accept Parser function or pointer to Parser function. Anything
else will panic.
* When using invalid regular expression to match a token.
Examples
--------
* expr/expr.go, implements a parsec grammar to parse arithmetic expressions.
* json/json.go, implements a parsec grammar to parse JSON document.
Clone the repository run the benchmark suite
```bash
$ cd expr/
$ go test -test.bench=. -test.benchmem=true
$ cd json/
$ go test -test.bench=. -test.benchmem=true
```
To run the example program,
```bash
# to parse expression
$ go run tools/parsec/parsec.go -expr "10 + 29"
# to parse JSON string
$ go run tools/parsec/parsec.go -json '{ "key1" : [10, "hello", true, null, false] }'
```
Projects using goparsec
-----------------------
* [Monster](https://github.com/prataprc/monster), production system in golang.
* [GoLedger](https://github.com/tn47/goledger), ledger re-write in golang.
If your project is using goparsec you can raise an issue to list them under
this section.
Articles
--------
* [Parsing by composing functions][article1-link]
* [Parser composition for recursive grammar][article2-link]
* [How to use the ``Maybe`` combinator][article3-link]
How to contribute
-----------------
[](http://issuestats.com/github/prataprc/goparsec)
[](http://issuestats.com/github/prataprc/goparsec)
* Pick an issue, or create an new issue. Provide adequate documentation for
the issue.
* Assign the issue or get it assigned.
* Work on the code, once finished, raise a pull request.
* Goparsec is written in [golang](https://golang.org/), hence expected to
follow the global guidelines for writing go programs.
* If the changeset is more than few lines, please generate a
[report card][report-link].
* As of now, branch ``master`` is the development branch.
[theory-link]: http://en.wikipedia.org/wiki/Parser_combinator
[regexp-link]: https://golang.org/pkg/regexp
[ast-link]: http://godoc.org/github.com/prataprc/goparsec#AST
[goparsec-godoc-link]: http://godoc.org/github.com/prataprc/goparsec
[htmlparsec-link]: https://github.com/prataprc/goparsec/blob/master/html_test.go
[astquery-link]: https://prataprc.github.io/astquery.io
[article1-link]: http://prataprc.github.io/parser-combinator-composition.html
[article2-link]: http://prataprc.github.io/parser-combinator-recursive.html
[article3-link]: http://prataprc.github.io/parser-combinator-maybe.html
[report-link]: https://goreportcard.com/report/github.com/prataprc/goparsec