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// Package astfmt implements `ast.Node` formatting with fmt-like API.
package astfmt
import (
"bytes"
"fmt"
"go/ast"
"go/printer"
"go/token"
"io"
)
// Println calls fmt.Println with additional support of %s format
// for ast.Node arguments.
//
// Uses empty file set for AST printing.
func Println(args ...interface{}) error {
return defaultPrinter.Println(args...)
}
// Fprintf calls fmt.Fprintf with additional support of %s format
// for ast.Node arguments.
//
// Uses empty file set for AST printing.
func Fprintf(w io.Writer, format string, args ...interface{}) error {
return defaultPrinter.Fprintf(w, format, args...)
}
// Sprintf calls fmt.Sprintf with additional support of %s format
// for ast.Node arguments.
//
// Uses empty file set for AST printing.
func Sprintf(format string, args ...interface{}) string {
return defaultPrinter.Sprintf(format, args...)
}
// Sprint calls fmt.Sprint with additional support of %s format
// for ast.Node arguments.
//
// Uses empty file set for AST printing.
func Sprint(args ...interface{}) string {
return defaultPrinter.Sprint(args...)
}
// NewPrinter returns printer that uses bound file set when printing AST nodes.
func NewPrinter(fset *token.FileSet) *Printer {
return &Printer{fset: fset}
}
// Printer provides API close to fmt package for printing AST nodes.
// Unlike freestanding functions from this package, it makes it possible
// to associate appropriate file set for better output.
type Printer struct {
fset *token.FileSet
}
// Println printer method is like Println function, but uses bound file set when printing.
func (p *Printer) Println(args ...interface{}) error {
_, err := fmt.Println(wrapArgs(p.fset, args)...)
return err
}
// Fprintf printer method is like Fprintf function, but uses bound file set when printing.
func (p *Printer) Fprintf(w io.Writer, format string, args ...interface{}) error {
_, err := fmt.Fprintf(w, format, wrapArgs(p.fset, args)...)
return err
}
// Sprintf printer method is like Sprintf function, but uses bound file set when printing.
func (p *Printer) Sprintf(format string, args ...interface{}) string {
return fmt.Sprintf(format, wrapArgs(p.fset, args)...)
}
// Sprint printer method is like Sprint function, but uses bound file set when printing.
func (p *Printer) Sprint(args ...interface{}) string {
return fmt.Sprint(wrapArgs(p.fset, args)...)
}
// defaultPrinter is used in printing functions like Println.
// Uses empty file set.
var defaultPrinter = NewPrinter(token.NewFileSet())
// wrapArgs returns arguments slice with every ast.Node element
// replaced with fmtNode wrapper that supports additional formatting.
func wrapArgs(fset *token.FileSet, args []interface{}) []interface{} {
for i := range args {
if x, ok := args[i].(ast.Node); ok {
args[i] = fmtNode{fset: fset, node: x}
}
}
return args
}
type fmtNode struct {
fset *token.FileSet
node ast.Node
}
func (n fmtNode) String() string {
var buf bytes.Buffer
if err := printer.Fprint(&buf, n.fset, n.node); err != nil {
return fmt.Sprintf("%%!s(ast.Node=%s)", err)
}
return buf.String()
}
func (n fmtNode) GoString() string {
var buf bytes.Buffer
fmt.Fprintf(&buf, "%#v", n.node)
return buf.String()
}
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