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118 lines
3.7 KiB
118 lines
3.7 KiB
// Go support for Protocol Buffers - Google's data interchange format
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//
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// Copyright 2017 The Go Authors. All rights reserved.
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// https://github.com/golang/protobuf
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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/*
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Package remap handles tracking the locations of Go tokens in a source text
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across a rewrite by the Go formatter.
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*/
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package remap
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import (
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"fmt"
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"go/scanner"
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"go/token"
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)
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// A Location represents a span of byte offsets in the source text.
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type Location struct {
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Pos, End int // End is exclusive
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}
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// A Map represents a mapping between token locations in an input source text
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// and locations in the corresponding output text.
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type Map map[Location]Location
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// Find reports whether the specified span is recorded by m, and if so returns
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// the new location it was mapped to. If the input span was not found, the
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// returned location is the same as the input.
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func (m Map) Find(pos, end int) (Location, bool) {
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key := Location{
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Pos: pos,
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End: end,
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}
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if loc, ok := m[key]; ok {
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return loc, true
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}
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return key, false
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}
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func (m Map) add(opos, oend, npos, nend int) {
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m[Location{Pos: opos, End: oend}] = Location{Pos: npos, End: nend}
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}
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// Compute constructs a location mapping from input to output. An error is
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// reported if any of the tokens of output cannot be mapped.
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func Compute(input, output []byte) (Map, error) {
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itok := tokenize(input)
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otok := tokenize(output)
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if len(itok) != len(otok) {
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return nil, fmt.Errorf("wrong number of tokens, %d ≠ %d", len(itok), len(otok))
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}
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m := make(Map)
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for i, ti := range itok {
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to := otok[i]
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if ti.Token != to.Token {
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return nil, fmt.Errorf("token %d type mismatch: %s ≠ %s", i+1, ti, to)
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}
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m.add(ti.pos, ti.end, to.pos, to.end)
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}
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return m, nil
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}
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// tokinfo records the span and type of a source token.
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type tokinfo struct {
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pos, end int
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token.Token
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}
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func tokenize(src []byte) []tokinfo {
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fs := token.NewFileSet()
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var s scanner.Scanner
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s.Init(fs.AddFile("src", fs.Base(), len(src)), src, nil, scanner.ScanComments)
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var info []tokinfo
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for {
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pos, next, lit := s.Scan()
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switch next {
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case token.SEMICOLON:
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continue
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}
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info = append(info, tokinfo{
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pos: int(pos - 1),
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end: int(pos + token.Pos(len(lit)) - 1),
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Token: next,
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})
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if next == token.EOF {
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break
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}
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}
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return info
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}
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