package printer

Import Path
	go/printer (on go.dev)

Dependency Relation
	imports 15 packages, and imported by one package


Involved Source Files

	    comment.go
	    gobuild.go
	    nodes.go
	
		Package printer implements printing of AST nodes.


Code Examples

	
		package main
		
		import (
			"bytes"
			"fmt"
			"go/ast"
			"go/parser"
			"go/printer"
			"go/token"
			"strings"
		)
		
		func parseFunc(filename, functionname string) (fun *ast.FuncDecl, fset *token.FileSet) {
			fset = token.NewFileSet()
			if file, err := parser.ParseFile(fset, filename, nil, 0); err == nil {
				for _, d := range file.Decls {
					if f, ok := d.(*ast.FuncDecl); ok && f.Name.Name == functionname {
						fun = f
						return
					}
				}
			}
			panic("function not found")
		}
		
		func printSelf() {
			// Parse source file and extract the AST without comments for
			// this function, with position information referring to the
			// file set fset.
			funcAST, fset := parseFunc("example_test.go", "printSelf")
		
			// Print the function body into buffer buf.
			// The file set is provided to the printer so that it knows
			// about the original source formatting and can add additional
			// line breaks where they were present in the source.
			var buf bytes.Buffer
			printer.Fprint(&buf, fset, funcAST.Body)
		
			// Remove braces {} enclosing the function body, unindent,
			// and trim leading and trailing white space.
			s := buf.String()
			s = s[1 : len(s)-1]
			s = strings.TrimSpace(strings.ReplaceAll(s, "\n\t", "\n"))
		
			// Print the cleaned-up body text to stdout.
			fmt.Println(s)
		}
		
		func main() {
			printSelf()
		
		}




Package-Level Type Names (total 3)


	/* sort by:  |  */
	
		A CommentedNode bundles an AST node and corresponding comments.
		It may be provided as argument to any of the [Fprint] functions.

		
			Comments []*ast.CommentGroup
			
				// *ast.File, or ast.Expr, ast.Decl, ast.Spec, or ast.Stmt



	
		A Config node controls the output of Fprint.

		
			
				// default: 0 (all code is indented at least by this much)

			
				// default: 0

			
				// default: 8

		
			
				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].



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

		
			const RawFormat
			const SourcePos
			const TabIndent
			const UseSpaces




Package-Level Functions (only one)


	
		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.




Package-Level Constants (total 4)


	const RawFormat Mode = 1 // do not use a tabwriter; if set, UseSpaces is ignored
	const SourcePos Mode = 8 // emit //line directives to preserve original source positions
	const TabIndent Mode = 2 // use tabs for indentation independent of UseSpaces
	const UseSpaces Mode = 4 // use spaces instead of tabs for alignment