package printer

import “go/printer”

Package printer implements printing of AST nodes..

Index 返回首页

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

// 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”, “ExampleFprint”)

// 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.Replace(s, “\n\t”, “\n”, -1))

// Print the cleaned-up body text to stdout. fmt.Println(s)

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.Replace(s, “\n\t”, “\n”, -1))

fmt.Println(s) 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 comments to preserve original source positions )