Documentation

Overview

    Package printer implements printing of AST nodes.

    Index

    Examples

    Constants

    This section is empty.

    Variables

    This section is empty.

    Functions

    func Fprint

    func Fprint(output io.Writer, fset *token.FileSet, node interface{}) 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
      Output:
      
      funcAST, fset := parseFunc("example_test.go", "ExampleFprint")
      
      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     interface{} // *ast.File, or ast.Expr, ast.Decl, ast.Spec, or ast.Stmt
      	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 // default: 0
        	Tabwidth int  // default: 8
        	Indent   int  // default: 0 (all code is indented at least by this much)
        }

          A Config node controls the output of Fprint.

          func (*Config) Fprint

          func (cfg *Config) Fprint(output io.Writer, fset *token.FileSet, node interface{}) 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 // do not use a tabwriter; if set, UseSpaces is ignored
              	TabIndent                  // use tabs for indentation independent of UseSpaces
              	UseSpaces                  // use spaces instead of tabs for alignment
              	SourcePos                  // emit //line directives to preserve original source positions
              )