cometkim / gaq

Gaq(Go Ast Query)

GAQ(Go AST Query)

GAQ is the library to query ast.Node children like JavaScript querySelector or querySelectorAll.

Table of Contents

• GAQ(Go AST Query)
  • Table of Contents
• Install
  • Library
    • Usage
  • CLI
    • Usage
• Query Specfication
  • Supported Combinators
  • Supported Attribute Syntax
  • Supported Pseudo Class

Install

Library

go get github.com/tamayika/gaq/pkg/gaq

Usage

Please refer pkg/gaq/example_test.go as

CLI

go get github.com/tamayika/gaq

Usage

You can see help with --help flag.

$ gaq --help
gaq is the cli tool to query ast node.
Typical usage is

  cat <go file path> | gaq <Query>

Please see details at https://github.com/tamayika/gaq

Usage:
  gaq <Query> [flags]

Flags:
  -h, --help   help for gaq

For example, File > Ident query filters package name in main.go

$ cat main.go | gaq "File > Ident"
main

Query Specfication

Heavily inspired by CSS Selector.

Query:
    Selector [',' Selector]

Selector:
    SimpleSelector [Combinator SimpleSelector]

SimpleSelector:
    NodeName [Attribute] [Pseudo]

Attribute:
    '[' Field [ AttributeOperator Value ] ']'

Pseudo:
    ':' Name [ '(' Expression ')' ]

Full used example

    File > Ident[Name*='test']:first-child, File > Ident[Name*='test']:last-child

Here, NodeName is one of node type of ast. For example, if you want to find *ast.StructType, NodeName is StructType. You can also specify * as any node type.

If you don't know NodeName, VSCode extension vscode-go-ast-explorer will help you to find it out.

Supported Combinators

Combinator	Name	Meaning
+	Adjacent sibling combinator	The second node directly follows the first, and both share the same parent.
~	General sibling combinator	The second node follows the first (though not necessarily immediately), and both share the same parent.
>	Child combinator	Selects nodes that are direct children of the first node.
(whitespace)	Descendant combinator	Selects nodes that are descendants of the first node.

Supported Attribute Syntax

Syntax	Meaning
[f]	Represents Node with an field name of f.
[f=value]	Represents Node with an field name of f whose value is exactly value.
[f~=value]	Represents Node with an field name of f whose value is a whitespace-separated list of words, one of which is exactly value.
[f|=value]	Represents Node with an field name of f whose value can be exactly value or can begin with value immediately followed by a hyphen, -.
[f^=value]	Represents Node with an field name of f whose value is prefixed (preceded) by value.
[f$=value]	Represents Node with an field name of f whose value is suffixed (followed) by value.
[f*=value]	Represents Node with an field name of f whose value contains at least one occurrence of value within the string.

Supported Pseudo Class

Syntax	Meaning
:first-child	Represents the first node among a group of sibling nodes.
:first-of-type	Represents the first node of its type among a group of sibling nodes.
:last-child	Represents the last node among a group of sibling nodes.
:last-of-type	Represents the last node of its type among a group of sibling nodes.