Golang File.Decls方法代码示例

func removeEmptyDeclGroups(f *ast.File) {
	i := 0
	for _, d := range f.Decls {
		if g, ok := d.(*ast.GenDecl); !ok || !isEmpty(f, g) {
			f.Decls[i] = d
			i++
		}
	}
	f.Decls = f.Decls[:i]
}

// fileExports removes unexported declarations from src in place.
//
func (r *reader) fileExports(src *ast.File) {
	j := 0
	for _, d := range src.Decls {
		if r.filterDecl(d) {
			src.Decls[j] = d
			j++
		}
	}
	src.Decls = src.Decls[0:j]
}

// sortImports sorts runs of consecutive import lines in import blocks in f.
// It also removes duplicate imports when it is possible to do so without data loss.
func sortImports(fset *token.FileSet, f *ast.File) {
	for i, d := range f.Decls {
		d, ok := d.(*ast.GenDecl)
		if !ok || d.Tok != token.IMPORT {
			// Not an import declaration, so we're done.
			// Imports are always first.
			break
		}

		if len(d.Specs) == 0 {
			// Empty import block, remove it.
			f.Decls = append(f.Decls[:i], f.Decls[i+1:]...)
		}

		if !d.Lparen.IsValid() {
			// Not a block: sorted by default.
			continue
		}

		// Identify and sort runs of specs on successive lines.
		i := 0
		specs := d.Specs[:0]
		for j, s := range d.Specs {
			if j > i && fset.Position(s.Pos()).Line > 1+fset.Position(d.Specs[j-1].End()).Line {
				// j begins a new run.  End this one.
				specs = append(specs, sortSpecs(fset, f, d.Specs[i:j])...)
				i = j
			}
		}
		specs = append(specs, sortSpecs(fset, f, d.Specs[i:])...)
		d.Specs = specs

		// Deduping can leave a blank line before the rparen; clean that up.
		if len(d.Specs) > 0 {
			lastSpec := d.Specs[len(d.Specs)-1]
			lastLine := fset.Position(lastSpec.Pos()).Line
			if rParenLine := fset.Position(d.Rparen).Line; rParenLine > lastLine+1 {
				fset.File(d.Rparen).MergeLine(rParenLine - 1)
			}
		}
	}
}

// AddNamedImport adds the import path to the file f, if absent.
// If name is not empty, it is used to rename the import.
//
// For example, calling
//	AddNamedImport(fset, f, "pathpkg", "path")
// adds
//	import pathpkg "path"
func AddNamedImport(fset *token.FileSet, f *ast.File, name, ipath string) (added bool) {
	if imports(f, ipath) {
		return false
	}

	newImport := &ast.ImportSpec{
		Path: &ast.BasicLit{
			Kind:  token.STRING,
			Value: strconv.Quote(ipath),
		},
	}
	if name != "" {
		newImport.Name = &ast.Ident{Name: name}
	}

	// Find an import decl to add to.
	// The goal is to find an existing import
	// whose import path has the longest shared
	// prefix with ipath.
	var (
		bestMatch  = -1         // length of longest shared prefix
		lastImport = -1         // index in f.Decls of the file's final import decl
		impDecl    *ast.GenDecl // import decl containing the best match
		impIndex   = -1         // spec index in impDecl containing the best match
	)
	for i, decl := range f.Decls {
		gen, ok := decl.(*ast.GenDecl)
		if ok && gen.Tok == token.IMPORT {
			lastImport = i
			// Do not add to import "C", to avoid disrupting the
			// association with its doc comment, breaking cgo.
			if declImports(gen, "C") {
				continue
			}

			// Match an empty import decl if that's all that is available.
			if len(gen.Specs) == 0 && bestMatch == -1 {
				impDecl = gen
			}

			// Compute longest shared prefix with imports in this group.
			for j, spec := range gen.Specs {
				impspec := spec.(*ast.ImportSpec)
				n := matchLen(importPath(impspec), ipath)
				if n > bestMatch {
					bestMatch = n
					impDecl = gen
					impIndex = j
				}
			}
		}
	}

	// If no import decl found, add one after the last import.
	if impDecl == nil {
		impDecl = &ast.GenDecl{
			Tok: token.IMPORT,
		}
		if lastImport >= 0 {
			impDecl.TokPos = f.Decls[lastImport].End()
		} else {
			// There are no existing imports.
			// Our new import goes after the package declaration and after
			// the comment, if any, that starts on the same line as the
			// package declaration.
			impDecl.TokPos = f.Package

			file := fset.File(f.Package)
			pkgLine := file.Line(f.Package)
			for _, c := range f.Comments {
				if file.Line(c.Pos()) > pkgLine {
					break
				}
				impDecl.TokPos = c.End()
			}
		}
		f.Decls = append(f.Decls, nil)
		copy(f.Decls[lastImport+2:], f.Decls[lastImport+1:])
		f.Decls[lastImport+1] = impDecl
	}

	// Insert new import at insertAt.
	insertAt := 0
	if impIndex >= 0 {
		// insert after the found import
		insertAt = impIndex + 1
	}
	impDecl.Specs = append(impDecl.Specs, nil)
	copy(impDecl.Specs[insertAt+1:], impDecl.Specs[insertAt:])
	impDecl.Specs[insertAt] = newImport
	pos := impDecl.Pos()
	if insertAt > 0 {
		// If there is a comment after an existing import, preserve the comment
//.........这里部分代码省略.........

// DeleteNamedImport deletes the import with the given name and path from the file f, if present.
func DeleteNamedImport(fset *token.FileSet, f *ast.File, name, path string) (deleted bool) {
	var delspecs []*ast.ImportSpec

	// Find the import nodes that import path, if any.
	for i := 0; i < len(f.Decls); i++ {
		decl := f.Decls[i]
		gen, ok := decl.(*ast.GenDecl)
		if !ok || gen.Tok != token.IMPORT {
			continue
		}
		for j := 0; j < len(gen.Specs); j++ {
			spec := gen.Specs[j]
			impspec := spec.(*ast.ImportSpec)
			if impspec.Name == nil && name != "" {
				continue
			}
			if impspec.Name != nil && impspec.Name.Name != name {
				continue
			}
			if importPath(impspec) != path {
				continue
			}

			// We found an import spec that imports path.
			// Delete it.
			delspecs = append(delspecs, impspec)
			deleted = true
			copy(gen.Specs[j:], gen.Specs[j+1:])
			gen.Specs = gen.Specs[:len(gen.Specs)-1]

			// If this was the last import spec in this decl,
			// delete the decl, too.
			if len(gen.Specs) == 0 {
				copy(f.Decls[i:], f.Decls[i+1:])
				f.Decls = f.Decls[:len(f.Decls)-1]
				i--
				break
			} else if len(gen.Specs) == 1 {
				gen.Lparen = token.NoPos // drop parens
			}
			if j > 0 {
				lastImpspec := gen.Specs[j-1].(*ast.ImportSpec)
				lastLine := fset.Position(lastImpspec.Path.ValuePos).Line
				line := fset.Position(impspec.Path.ValuePos).Line

				// We deleted an entry but now there may be
				// a blank line-sized hole where the import was.
				if line-lastLine > 1 {
					// There was a blank line immediately preceding the deleted import,
					// so there's no need to close the hole.
					// Do nothing.
				} else {
					// There was no blank line. Close the hole.
					fset.File(gen.Rparen).MergeLine(line)
				}
			}
			j--
		}
	}

	// Delete them from f.Imports.
	for i := 0; i < len(f.Imports); i++ {
		imp := f.Imports[i]
		for j, del := range delspecs {
			if imp == del {
				copy(f.Imports[i:], f.Imports[i+1:])
				f.Imports = f.Imports[:len(f.Imports)-1]
				copy(delspecs[j:], delspecs[j+1:])
				delspecs = delspecs[:len(delspecs)-1]
				i--
				break
			}
		}
	}

	if len(delspecs) > 0 {
		panic(fmt.Sprintf("deleted specs from Decls but not Imports: %v", delspecs))
	}

	return
}