// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package token_test
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import (
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"fmt"
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"go/ast"
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"go/parser"
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"go/token"
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)
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func Example_retrievePositionInfo() {
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fset := token.NewFileSet()
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const src = `package main
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import "fmt"
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import "go/token"
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//line :1:5
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type p = token.Pos
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const bad = token.NoPos
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//line fake.go:42:11
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func ok(pos p) bool {
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return pos != bad
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}
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/*line :7:9*/func main() {
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fmt.Println(ok(bad) == bad.IsValid())
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}
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`
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f, err := parser.ParseFile(fset, "main.go", src, 0)
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if err != nil {
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fmt.Println(err)
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return
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}
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// Print the location and kind of each declaration in f.
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for _, decl := range f.Decls {
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// Get the filename, line, and column back via the file set.
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// We get both the relative and absolute position.
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// The relative position is relative to the last line directive.
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// The absolute position is the exact position in the source.
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pos := decl.Pos()
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relPosition := fset.Position(pos)
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absPosition := fset.PositionFor(pos, false)
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// Either a FuncDecl or GenDecl, since we exit on error.
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kind := "func"
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if gen, ok := decl.(*ast.GenDecl); ok {
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kind = gen.Tok.String()
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}
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// If the relative and absolute positions differ, show both.
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fmtPosition := relPosition.String()
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if relPosition != absPosition {
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fmtPosition += "[" + absPosition.String() + "]"
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}
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fmt.Printf("%s: %s\n", fmtPosition, kind)
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}
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//Output:
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//
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// main.go:3:1: import
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// main.go:5:1: import
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// main.go:1:5[main.go:8:1]: type
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// main.go:3:1[main.go:10:1]: const
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// fake.go:42:11[main.go:13:1]: func
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// fake.go:7:9[main.go:17:14]: func
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}
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