package printer

Import Path
	go/printer (on go.dev)

Dependency Relation
	imports 15 packages, and imported by 2 packages


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