jnwhiteh/go-luapatterns

---

jnwhiteh/go-luapatterns.json

{
  "createdAt": "2010-06-23T16:49:35Z",
  "defaultBranch": "master",
  "description": "A pure Go implementation of Lua pattern matching",
  "fullName": "jnwhiteh/go-luapatterns",
  "homepage": "",
  "language": "Go",
  "name": "go-luapatterns",
  "pushedAt": "2013-10-30T16:45:48Z",
  "stargazersCount": 23,
  "topics": [],
  "updatedAt": "2024-01-18T04:01:26Z",
  "url": "https://github.com/jnwhiteh/go-luapatterns"
}

A pure Go implementation of Lua pattern matching

Introduction

The package implements a subset of Lua patterns in Go. It is not an idiomatic port, but rather uses as close to a line-by-line translation of the original C source. This means this package incurs quite a bit of overhead by implementing a string pointer type. I have still found the speed to be rather acceptable for most pattern matching needs.

Currently the following function equivalents are implemented:

• string.match as Match/MatchBytes
• string.gmatch as Gmatch/GmatchBytes
• string.find as Find/FindBytes
• string.gsub as Replace/ReplaceBytes

Installing

You can install the package using [go install][4]

go install github.com/jnwhiteh/go-luapatterns/pattern

Updating

If you would like to update to the latest version of luapatterns, simply use the goinstall flag to accomplish this:

go install github.com/jnwhiteh/go-luapatterns/luapatterns

Using

Once you have installed the package using goinstall, you can use the package in the following manner:

    package main

    import "fmt"
    import pattern "github.com/jnwhiteh/go-luapatterns/luapatterns"

    func main() {
      str := "aaaaab"
      pat := "(.-)(b)"
      succ, caps := pattern.Match(str, pat)

      fmt.Printf("Match('%s', '%s') => %t\n", str, pat, succ)
      for idx, capture := range caps {
        fmt.Printf("capture[%d] = '%s'\n", idx, capture)
      }
    }

Reference

The documentation for Lua patterns can be found on the [Lua Reference Manual - Section 5.4.1][3].

Differences

• This implementation drops the use of the ‘init’ argument to the find function, since if you would like to start finding a pattern at a point in the string, you can take a sub-slice in order to do this.
• The indices returns from Find will not match the returns from the equivalent Lua program due to differences in array indexing (start will be -1) and slices. In order to get the substring of a pattern match, you can take str[startIndex:endIndex].
• The Replace function is the string-only version of gsub. There is currently no function/table lookup equivalent.
• The Gmatch function is not a translation of the Lua version, it is a simple naive implementation based on index tracking and Find.

Known Issues

• Position captures are not currently implemented, as I am unsure how to return those values to the caller.
• The frontier pattern %f is not working properly

Resources

• [Lua 5.1 Reference Manual][2]
• [Kahlua String Library][1]

[1] !: http://github.com/krka/kahlua2/blob/master/core/src/se/krka/kahlua/stdlib/StringLib.java [2] !: http://www.lua.org/manual/5.1/manual.html [3] !: http://www.lua.org/manual/5.1/manual.html#5.4.1 [4] !: http://golang.org/cmd/goinstall/