https://github.com/andremm/lua-parser
A Lua 5.3 parser written with LPegLabel
https://github.com/andremm/lua-parser
Last synced: 11 months ago
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A Lua 5.3 parser written with LPegLabel
- Host: GitHub
- URL: https://github.com/andremm/lua-parser
- Owner: andremm
- License: mit
- Created: 2014-01-09T11:04:57.000Z (about 12 years ago)
- Default Branch: main
- Last Pushed: 2025-03-11T15:35:22.000Z (about 1 year ago)
- Last Synced: 2025-03-28T07:04:03.707Z (12 months ago)
- Language: Lua
- Homepage:
- Size: 97.7 KB
- Stars: 197
- Watchers: 12
- Forks: 29
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-lua - lua-parser - A Lua 5.3 parser written using LPegLabel, with improved error messages. (Resources / Analysis Tools and ASTs)
README
lua-parser
==========
[](https://travis-ci.org/andremm/lua-parser)
This is a Lua 5.3 parser written with [LPegLabel](https://github.com/sqmedeiros/lpeglabel) that
generates an AST in a format that is similar to the one specified by [Metalua](https://github.com/fab13n/metalua-parser).
The parser uses LPegLabel to provide more specific error messages.
Requirements
------------
lua >= 5.1
lpeglabel >= 1.6.0
API
---
The package `lua-parser` has two modules: `lua-parser.parser`
and `lua-parser.pp`.
The module `lua-parser.parser` implements the function `parser.parse`:
* `parser.parse (subject, filename)`
Both subject and filename should be strings.
It tries to parse subject and returns the AST in case of success.
It returns **nil** plus an error message in case of error.
In case of error, the parser uses the string filename to build an
error message.
The module `lua-parser.pp` implements a pretty printer to the AST and
a dump function:
* `pp.tostring (ast)`
It converts the AST to a string and returns this string.
* `pp.print (ast)`
It converts the AST to a string and prints this string.
* `pp.dump (ast[, i])`
It dumps the AST to the screen.
The parameter **i** sets the indentation level.
AST format
----------
block: { stat* }
stat:
`Do{ stat* }
| `Set{ {lhs+} {expr+} } -- lhs1, lhs2... = e1, e2...
| `While{ expr block } -- while e do b end
| `Repeat{ block expr } -- repeat b until e
| `If{ (expr block)+ block? } -- if e1 then b1 [elseif e2 then b2] ... [else bn] end
| `Fornum{ ident expr expr expr? block } -- for ident = e, e[, e] do b end
| `Forin{ {ident+} {expr+} block } -- for i1, i2... in e1, e2... do b end
| `Local{ {ident+} {expr+}? } -- local i1, i2... = e1, e2...
| `Localrec{ ident expr } -- only used for 'local function'
| `Goto{ } -- goto str
| `Label{ } -- ::str::
| `Return{ } -- return e1, e2...
| `Break -- break
| apply
expr:
`Nil
| `Dots
| `Boolean{ }
| `Number{ }
| `String{ }
| `Function{ { `Id{ }* `Dots? } block }
| `Table{ ( `Pair{ expr expr } | expr )* }
| `Op{ opid expr expr? }
| `Paren{ expr } -- significant to cut multiple values returns
| apply
| lhs
apply:
`Call{ expr expr* }
| `Invoke{ expr `String{ } expr* }
lhs: `Id{ } | `Index{ expr expr }
opid: -- includes additional operators from Lua 5.3 and all relational operators
'add' | 'sub' | 'mul' | 'div'
| 'idiv' | 'mod' | 'pow' | 'concat'
| 'band' | 'bor' | 'bxor' | 'shl' | 'shr'
| 'eq' | 'ne' | 'lt' | 'gt' | 'le' | 'ge'
| 'and' | 'or' | 'unm' | 'len' | 'bnot' | 'not'
Usage
--------
**Code example for parsing a string:**
local parser = require "lua-parser.parser"
local pp = require "lua-parser.pp"
if #arg ~= 1 then
print("Usage: parse.lua ")
os.exit(1)
end
local ast, error_msg = parser.parse(arg[1], "example.lua")
if not ast then
print(error_msg)
os.exit(1)
end
pp.print(ast)
os.exit(0)
**Running the above code example using a string without syntax error:**
$ lua parse.lua "for i=1, 10 do print(i) end"
{ `Fornum{ `Id "i", `Number "1", `Number "10", { `Call{ `Id "print", `Id "i" } } } }
**Running the above code example using a string with syntax error:**
$ lua parse.lua "for i=1, 10 do print(i) "
example.lua:1:24: syntax error, expected 'end' to close the for loop