printer

Documentation

Overview

Package printer implements printing of AST nodes.

Index

• func Fprint(output io.Writer, fset *token.FileSet, node any) error
• type CommentedNode
• type Config
  • func (cfg *Config) Fprint(output io.Writer, fset *token.FileSet, node any) error
• type Mode

Examples

• Fprint

Functions

func Fprint

func Fprint(output io.Writer, fset *token.FileSet, node any) error

Fprint "pretty-prints" an AST node to output. It calls Config.Fprint with default settings. Note that gofmt uses tabs for indentation but spaces for alignment; use format.Node (package go/format) for output that matches gofmt.

Example

printSelf()

Output:
funcAST, fset := parseFunc("example_test.go", "printSelf")

var buf bytes.Buffer
printer.Fprint(&buf, fset, funcAST.Body)

s := buf.String()
s = s[1 : len(s)-1]
s = strings.TrimSpace(strings.ReplaceAll(s, "\n\t", "\n"))

fmt.Println(s)

Types

type CommentedNode

type CommentedNode struct {
	Node     any
	Comments []*ast.CommentGroup
}

A CommentedNode bundles an AST node and corresponding comments. It may be provided as argument to any of the Fprint functions.

type Config

type Config struct {
	Mode     Mode
	Tabwidth int
	Indent   int
}

A Config node controls the output of Fprint.

func (*Config) Fprint

func (cfg *Config) Fprint(output io.Writer, fset *token.FileSet, node any) error

Fprint "pretty-prints" an AST node to output for a given configuration cfg. Position information is interpreted relative to the file set fset. The node type must be *ast.File, *CommentedNode, []ast.Decl, []ast.Stmt, or assignment-compatible to ast.Expr, ast.Decl, ast.Spec, or ast.Stmt.

type Mode

type Mode uint

A Mode value is a set of flags (or 0). They control printing.

const (
	RawFormat Mode = 1 << iota
	TabIndent
	UseSpaces
	SourcePos
)