gopygo

Pure Python Go parser, AST and unparser library

Installation

$ pip3 install gopygo

Usage

Parse and unparse the Go Hello, World! example:

>>> import gopygo
>>> program = """
... package main
... 
... import "fmt"
... 
... func main() {
...     fmt.Println("Hello, World!")
... }
... """
>>> program = program.lstrip()
>>> tree = gopygo.parse(program)
>>> tree
<gopygo.ast.File object at 0x7f0b5dddb6d0>
>>> tree.__dict__
{'name': <gopygo.ast.Package object at 0x7f0b5dddb0a0>, 'imports': [<gopygo.ast.ImportSpec object at 0x7f0b5dddb190>], 'decls': [<gopygo.ast.FuncDecl object at 0x7f0b5dddb520>]}
>>> text = gopygo.unparse(tree)
>>> print(text)
package main

import "fmt"

func main() {
    fmt.Println("Hello, World!")
}

>>> assert program == text

Roadmap

Implement the AST nodes specified in here and the parser, unparser libraries accordingly.

Tokens are defined in here.

Development

Here is an example access Go AST using original go/parser and go/ast packages:

package main

import "fmt"
import "go/token"
import "go/parser"
import "go/ast"

func main() {
	src := `
package main

import "fmt"

func main() {
    fmt.Println("Hello, World!")
}
	`
	x, err := parser.ParseFile(token.NewFileSet(), "", src, 0)
	fmt.Println(x.Decls[1].(*ast.FuncDecl).Body.List[0].(*ast.ExprStmt).X.(*ast.CallExpr).Args[0].(*ast.BasicLit).Value)
	fmt.Println(err)
	fmt.Printf("type: %T\n", x.Decls[1].(*ast.FuncDecl).Body.List[0].(*ast.ExprStmt).X.(*ast.CallExpr).Args[0].(*ast.BasicLit).Value)
}

Gives this output:

"Hello, World!"
<nil>
type: string