Курнат Андрей
83 lines
1.5 KiB
Go
83 lines
1.5 KiB
Go
// Copyright 2018 The OPA Authors. All rights reserved.
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// Use of this source code is governed by an Apache2
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// license that can be found in the LICENSE file.
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package ast
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import (
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"fmt"
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"io"
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"strings"
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)
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// Pretty writes a pretty representation of the AST rooted at x to w.
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//
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// This is function is intended for debug purposes when inspecting ASTs.
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func Pretty(w io.Writer, x any) {
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pp := &prettyPrinter{
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depth: -1,
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w: w,
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}
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NewBeforeAfterVisitor(pp.Before, pp.After).Walk(x)
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}
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type prettyPrinter struct {
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depth int
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w io.Writer
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}
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func (pp *prettyPrinter) Before(x any) bool {
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switch x.(type) {
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case *Term:
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default:
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pp.depth++
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}
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switch x := x.(type) {
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case *Term:
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return false
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case Args:
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if len(x) == 0 {
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return false
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}
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pp.writeType(x)
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case *Expr:
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extras := []string{}
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if x.Negated {
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extras = append(extras, "negated")
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}
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extras = append(extras, fmt.Sprintf("index=%d", x.Index))
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pp.writeIndent("%v %v", TypeName(x), strings.Join(extras, " "))
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case Null, Boolean, Number, String, Var:
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pp.writeValue(x)
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default:
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pp.writeType(x)
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}
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return false
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}
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func (pp *prettyPrinter) After(x any) {
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switch x.(type) {
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case *Term:
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default:
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pp.depth--
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}
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}
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func (pp *prettyPrinter) writeValue(x any) {
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pp.writeIndent(fmt.Sprint(x))
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}
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func (pp *prettyPrinter) writeType(x any) {
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pp.writeIndent(TypeName(x))
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}
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func (pp *prettyPrinter) writeIndent(f string, a ...any) {
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pad := strings.Repeat(" ", pp.depth)
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pp.write(pad+f, a...)
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}
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func (pp *prettyPrinter) write(f string, a ...any) {
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fmt.Fprintf(pp.w, f+"\n", a...)
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}
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