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diff --git a/devdocs/go/go%2Fprinter%2Findex.html b/devdocs/go/go%2Fprinter%2Findex.html new file mode 100644 index 00000000..b801c989 --- /dev/null +++ b/devdocs/go/go%2Fprinter%2Findex.html @@ -0,0 +1,100 @@ +<h1> Package printer </h1> <ul id="short-nav"> +<li><code>import "go/printer"</code></li> +<li><a href="#pkg-overview" class="overviewLink">Overview</a></li> +<li><a href="#pkg-index" class="indexLink">Index</a></li> +<li><a href="#pkg-examples" class="examplesLink">Examples</a></li> +</ul> <h2 id="pkg-overview">Overview </h2> <p>Package printer implements printing of AST nodes. </p> <h2 id="pkg-index">Index </h2> <ul id="manual-nav"> +<li><a href="#Fprint">func Fprint(output io.Writer, fset *token.FileSet, node any) error</a></li> +<li><a href="#CommentedNode">type CommentedNode</a></li> +<li><a href="#Config">type Config</a></li> +<li> <a href="#Config.Fprint">func (cfg *Config) Fprint(output io.Writer, fset *token.FileSet, node any) error</a> +</li> +<li><a href="#Mode">type Mode</a></li> +</ul> <div id="pkg-examples"> <h3>Examples</h3> <dl> <dd><a class="exampleLink" href="#example_Fprint">Fprint</a></dd> </dl> </div> <h3>Package files</h3> <p> <span>comment.go</span> <span>gobuild.go</span> <span>nodes.go</span> <span>printer.go</span> </p> <h2 id="Fprint">func <span>Fprint</span> </h2> <pre data-language="go">func Fprint(output io.Writer, fset *token.FileSet, node any) error</pre> <p>Fprint "pretty-prints" an AST node to output. It calls <a href="#Config.Fprint">Config.Fprint</a> 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. </p> <h4 id="example_Fprint"> <span class="text">Example</span> +</h4> <p>Code:</p> <pre class="code" data-language="go">package printer_test + +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 ExampleFprint() { + 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) +} +</pre> <h2 id="CommentedNode">type <span>CommentedNode</span> </h2> <p>A CommentedNode bundles an AST node and corresponding comments. It may be provided as argument to any of the <a href="#Fprint">Fprint</a> functions. </p> +<pre data-language="go">type CommentedNode struct { + Node any // *ast.File, or ast.Expr, ast.Decl, ast.Spec, or ast.Stmt + Comments []*ast.CommentGroup +} +</pre> <h2 id="Config">type <span>Config</span> </h2> <p>A Config node controls the output of Fprint. </p> +<pre data-language="go">type Config struct { + Mode Mode // default: 0 + Tabwidth int // default: 8 + Indent int // default: 0 (all code is indented at least by this much); added in Go 1.1 +} +</pre> <h3 id="Config.Fprint">func (*Config) <span>Fprint</span> </h3> <pre data-language="go">func (cfg *Config) Fprint(output io.Writer, fset *token.FileSet, node any) error</pre> <p>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 *<span>ast.File</span>, *<a href="#CommentedNode">CommentedNode</a>, []<span>ast.Decl</span>, []<span>ast.Stmt</span>, or assignment-compatible to <span>ast.Expr</span>, <span>ast.Decl</span>, <span>ast.Spec</span>, or <span>ast.Stmt</span>. </p> +<h2 id="Mode">type <span>Mode</span> </h2> <p>A Mode value is a set of flags (or 0). They control printing. </p> +<pre data-language="go">type Mode uint</pre> <pre data-language="go">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 +)</pre><div class="_attribution"> + <p class="_attribution-p"> + © Google, Inc.<br>Licensed under the Creative Commons Attribution License 3.0.<br> + <a href="http://golang.org/pkg/go/printer/" class="_attribution-link">http://golang.org/pkg/go/printer/</a> + </p> +</div> |