luaparser 2.0.1

A lua parser in Python

py-lua-parser

A Lua parser and AST builder written in Python.

Installation:

The package can be installed through pip:

$ python3.6 -m pip install luaparser

It will install the shell command ‘luaparser’.

Options

These are the command-line flags:

Usage: luaparser [options] filename

CLI Options:
  --version                     Show program's version number and exit
  -h, --help                    Show this help message and exit
  -s, --source                  Source passed in a string
  -x, --xml                     Set output format to xml
  -o, --output                  Write output to file

Quickstart

Working on AST tree

Minimal exemple:

from luaparser import ast

src = """
    local function sayHello()
      print('hello world !')
    end
    sayHello()
    """

tree = ast.parse(src)
print(ast.toPrettyStr(tree))

will display:

Chunk: {} 1 key
  body: {} 1 key
    Block: {} 1 key
      body: [] 2 items
        0: {} 1 key
          LocalFunction: {} 3 keys
            name: {} 1 key
              Name: {} 1 key
                id: "sayHello"
            args: [] 0 item
            body: [] 1 item
              0: {} 1 key
                Call: {} 2 keys
                  func: {} 1 key
                    Name: {} 1 key
                      id: "print"
                  args: [] 1 item
                    0: {} 1 key
                      String: {} 1 key
                        s: "hello world !"
        1: {} 1 key
          Call: {} 2 keys
            func: {} 1 key
              Name: {} 1 key
                id: "sayHello"
            args: [] 0 item

You can run through the list of all the nodes in the tree using ast.walk(tree):

from luaparser import ast
from luaparser import astnodes

tree = ast.parse("local foo = 'bar'")

for node in ast.walk(tree):
    if isinstance(node, astnodes.Name):
        process(node)

Alternatively, you can use a node visitor:

from luaparser import ast
from luaparser import astnodes

src = "local a = 42"

class NumberVisitor(ast.ASTVisitor):
    def visit_Number(self, node):
        print('Number value = ' + str(node.n))

tree = ast.parse(src)
NumberVisitor().visit(tree)

Working on tokens, modifying source code

Working directly on tokens is a convenient way to modify source code:

from luaparser import asttokens

src = "local a = 1"

atokens = asttokens.parse(src)
for token in atokens.types(asttokens.Tokens.NAME):
    token.value.text = 'foo'

print(atokens.toSource())

Will render:

local foo = 1

You can also work on both ast and tokens. In fact, you can retrieve and edit all tokens associated to a specific AST node.

The following example show how to automatically modify last argument in function call:

from luaparser import ast

src = """\
print('foo')
process(1, 2, 3)
"""

class CallVisitor(ast.ASTVisitor):
    def visit_Call(self, node):
        print('Call:', node.func.id)
        print('Args:', node.args.edit().toSource())
        print('Full line: ', node.edit().toSource())
        node.args.edit().last().text = 'replaced'

tree = ast.parse(src)
CallVisitor().visit(tree)

print(tree.edit().toSource())

Output is:

Call: print
Args: 'foo'
Full line:  print('foo')

Call: process
Args: 1, 2, 3
Full line:
process(1, 2, 3)

print(replaced)
process(1, 2, replaced)