github.com/maruel/nin@v0.0.0-20220112143044-f35891e3ce7e/depfile_parser.go

// Code generated by re2c, DO NOT EDIT.
// Copyright 2011 Google Inc. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package nin

import "errors"

// DepfileParser is the parser for the dependency information emitted by gcc's
// -M flags.
type DepfileParser struct {
	outs []string
	ins  []string
}

// Parse parses a dependency file.
//
// content must contain a terminating zero byte.
//
// Warning: mutate the slice content in-place.
//
// A note on backslashes in Makefiles, from reading the docs:
// Backslash-newline is the line continuation character.
// Backslash-# escapes a # (otherwise meaningful as a comment start).
// Backslash-% escapes a % (otherwise meaningful as a special).
// Finally, quoting the GNU manual, "Backslashes that are not in danger
// of quoting ‘%’ characters go unmolested."
// How do you end a line with a backslash?  The netbsd Make docs suggest
// reading the result of a shell command echoing a backslash!
//
// Rather than implement all of above, we follow what GCC/Clang produces:
// Backslashes escape a space or hash sign.
// When a space is preceded by 2N+1 backslashes, it is represents N backslashes
// followed by space.
// When a space is preceded by 2N backslashes, it represents 2N backslashes at
// the end of a filename.
// A hash sign is escaped by a single backslash. All other backslashes remain
// unchanged.
//
// If anyone actually has depfiles that rely on the more complicated
// behavior we can adjust this.
func (d *DepfileParser) Parse(content []byte) error {
	// in: current parser input point.
	// end: end of input.
	// parsingTargets: whether we are parsing targets or dependencies.
	in := 0
	end := len(content)
	if end > 0 && content[len(content)-1] != 0 {
		panic("internal error")
	}
	haveTarget := false
	parsingTargets := true
	poisonedInput := false
	for in < end {
		haveNewline := false
		// out: current output point (typically same as in, but can fall behind
		// as we de-escape backslashes).
		out := in
		// filename: start of the current parsed filename.
		filename := out
		backup := 0
		for {
			// start: beginning of the current parsed span.
			start := in
			yymarker := 0
			/*
			 re2c:define:YYCTYPE = "byte";
			 re2c:define:YYCURSOR = "l.input[p]";
			 re2c:define:YYMARKER = q;
			 re2c:yyfill:enable = 0;
			 re2c:flags:nested-ifs = 1;
			*/

			{
				var yych byte
				yych = content[in]
				switch yych {
				case 0x00:
					goto yy2
				case 0x01:
					fallthrough
				case 0x02:
					fallthrough
				case 0x03:
					fallthrough
				case 0x04:
					fallthrough
				case 0x05:
					fallthrough
				case 0x06:
					fallthrough
				case 0x07:
					fallthrough
				case 0x08:
					fallthrough
				case '\t':
					fallthrough
				case '\v':
					fallthrough
				case '\f':
					fallthrough
				case 0x0E:
					fallthrough
				case 0x0F:
					fallthrough
				case 0x10:
					fallthrough
				case 0x11:
					fallthrough
				case 0x12:
					fallthrough
				case 0x13:
					fallthrough
				case 0x14:
					fallthrough
				case 0x15:
					fallthrough
				case 0x16:
					fallthrough
				case 0x17:
					fallthrough
				case 0x18:
					fallthrough
				case 0x19:
					fallthrough
				case 0x1A:
					fallthrough
				case 0x1B:
					fallthrough
				case 0x1C:
					fallthrough
				case 0x1D:
					fallthrough
				case 0x1E:
					fallthrough
				case 0x1F:
					fallthrough
				case ' ':
					fallthrough
				case '"':
					fallthrough
				case '#':
					fallthrough
				case '&':
					fallthrough
				case '\'':
					fallthrough
				case '*':
					fallthrough
				case ';':
					fallthrough
				case '<':
					fallthrough
				case '>':
					fallthrough
				case '?':
					fallthrough
				case '^':
					fallthrough
				case '`':
					fallthrough
				case '|':
					fallthrough
				case 0x7F:
					goto yy4
				case '\n':
					goto yy6
				case '\r':
					goto yy8
				case '$':
					goto yy12
				case '\\':
					goto yy13
				default:
					goto yy9
				}
			yy2:
				in++
				{
					break
				}
			yy4:
				in++
			yy5:
				{
					// For any other character (e.g. whitespace), swallow it here,
					// allowing the outer logic to loop around again.
					break
				}
			yy6:
				in++
				{
					// A newline ends the current file name and the current rule.
					haveNewline = true
					break
				}
			yy8:
				in++
				yych = content[in]
				switch yych {
				case '\n':
					goto yy6
				default:
					goto yy5
				}
			yy9:
				in++
				yych = content[in]
				switch yych {
				case 0x00:
					fallthrough
				case 0x01:
					fallthrough
				case 0x02:
					fallthrough
				case 0x03:
					fallthrough
				case 0x04:
					fallthrough
				case 0x05:
					fallthrough
				case 0x06:
					fallthrough
				case 0x07:
					fallthrough
				case 0x08:
					fallthrough
				case '\t':
					fallthrough
				case '\n':
					fallthrough
				case '\v':
					fallthrough
				case '\f':
					fallthrough
				case '\r':
					fallthrough
				case 0x0E:
					fallthrough
				case 0x0F:
					fallthrough
				case 0x10:
					fallthrough
				case 0x11:
					fallthrough
				case 0x12:
					fallthrough
				case 0x13:
					fallthrough
				case 0x14:
					fallthrough
				case 0x15:
					fallthrough
				case 0x16:
					fallthrough
				case 0x17:
					fallthrough
				case 0x18:
					fallthrough
				case 0x19:
					fallthrough
				case 0x1A:
					fallthrough
				case 0x1B:
					fallthrough
				case 0x1C:
					fallthrough
				case 0x1D:
					fallthrough
				case 0x1E:
					fallthrough
				case 0x1F:
					fallthrough
				case ' ':
					fallthrough
				case '"':
					fallthrough
				case '#':
					fallthrough
				case '$':
					fallthrough
				case '&':
					fallthrough
				case '\'':
					fallthrough
				case '*':
					fallthrough
				case ';':
					fallthrough
				case '<':
					fallthrough
				case '>':
					fallthrough
				case '?':
					fallthrough
				case '\\':
					fallthrough
				case '^':
					fallthrough
				case '`':
					fallthrough
				case '|':
					fallthrough
				case 0x7F:
					goto yy11
				default:
					goto yy9
				}
			yy11:
				{
					// Got a span of plain text.
					l := in - start
					// Need to shift it over if we're overwriting backslashes.
					if out < start {
						copy(content[out:out+l], content[start:start+l])
					}
					out += l
					continue
				}
			yy12:
				in++
				yych = content[in]
				switch yych {
				case '$':
					goto yy14
				default:
					goto yy5
				}
			yy13:
				in++
				backup = yymarker
				yych = content[in]
				switch yych {
				case 0x00:
					goto yy5
				case '\n':
					goto yy17
				case '\r':
					goto yy19
				case ' ':
					goto yy21
				case '#':
					goto yy23
				case ':':
					goto yy25
				case '\\':
					goto yy27
				default:
					goto yy16
				}
			yy14:
				in++
				{
					// De-escape dollar character.
					content[out] = '$'
					out++
					continue
				}
			yy16:
				in++
				goto yy11
			yy17:
				in++
				{
					// A line continuation ends the current file name.
					break
				}
			yy19:
				in++
				yych = content[in]
				switch yych {
				case '\n':
					goto yy17
				default:
					goto yy20
				}
			yy20:
				yymarker = backup
				goto yy5
			yy21:
				in++
				{
					// 2N+1 backslashes plus space -> N backslashes plus space.
					l := in - start
					n := l/2 - 1
					if out < start {
						for i := 0; i < n; i++ {
							content[out+i] = '\\'
						}
					}
					out += n
					content[out] = ' '
					out++
					continue
				}
			yy23:
				in++
				{
					// De-escape hash sign, but preserve other leading backslashes.
					l := in - start
					if l > 2 && out < start {
						for i := 0; i < l-2; i++ {
							content[out+i] = '\\'
						}
					}
					out += l - 2
					content[out] = '#'
					out++
					continue
				}
			yy25:
				in++
				yych = content[in]
				switch yych {
				case 0x00:
					fallthrough
				case '\t':
					fallthrough
				case '\n':
					fallthrough
				case '\r':
					fallthrough
				case ' ':
					goto yy28
				default:
					goto yy26
				}
			yy26:
				{
					// De-escape colon sign, but preserve other leading backslashes.
					// Regular expression uses lookahead to make sure that no whitespace
					// nor EOF follows. In that case it'd be the : at the end of a target
					l := in - start
					if l > 2 && out < start {
						for i := 0; i < l-2; i++ {
							content[out+i] = '\\'
						}
					}
					out += l - 2
					content[out] = ':'
					out++
					continue
				}
			yy27:
				in++
				yych = content[in]
				switch yych {
				case 0x00:
					fallthrough
				case '\n':
					fallthrough
				case '\r':
					goto yy11
				case ' ':
					goto yy30
				case '#':
					goto yy23
				case ':':
					goto yy25
				case '\\':
					goto yy32
				default:
					goto yy16
				}
			yy28:
				in++
				{
					// Backslash followed by : and whitespace.
					// It is therefore normal text and not an escaped colon
					l := in - start - 1
					// Need to shift it over if we're overwriting backslashes.
					if out < start {
						copy(content[out:out+l], content[start:start+l])
					}
					out += l
					if content[in-1] == '\n' {
						haveNewline = true
					}
					break
				}
			yy30:
				in++
				{
					// 2N backslashes plus space -> 2N backslashes, end of filename.
					l := in - start
					if out < start {
						for i := 0; i < l-1; i++ {
							content[out+i] = '\\'
						}
					}
					out += l - 1
					break
				}
			yy32:
				in++
				yych = content[in]
				switch yych {
				case 0x00:
					fallthrough
				case '\n':
					fallthrough
				case '\r':
					goto yy11
				case ' ':
					goto yy21
				case '#':
					goto yy23
				case ':':
					goto yy25
				case '\\':
					goto yy27
				default:
					goto yy16
				}
			}

		}

		l := out - filename
		isDependency := !parsingTargets
		if l > 0 && content[filename+l-1] == ':' {
			l-- // Strip off trailing colon, if any.
			parsingTargets = false
			haveTarget = true
		}

		if l > 0 {
			piece := unsafeString(content[filename : filename+l])
			// If we've seen this as an input before, skip it.
			// TODO(maruel): Use a map[string]struct{} while constructing.
			pos := -1
			for i, v := range d.ins {
				if piece == v {
					pos = i
					break
				}
			}
			if pos == -1 {
				if isDependency {
					if poisonedInput {
						return errors.New("inputs may not also have inputs")
					}
					// New input.
					d.ins = append(d.ins, piece)
				} else {
					// Check for a new output.
					pos = -1
					for i, v := range d.outs {
						if piece == v {
							pos = i
							break
						}
					}
					if pos == -1 {
						d.outs = append(d.outs, piece)
					}
				}
			} else if !isDependency {
				// We've passed an input on the left side; reject new inputs.
				poisonedInput = true
			}
		}

		if haveNewline {
			// A newline ends a rule so the next filename will be a new target.
			parsingTargets = true
			poisonedInput = false
		}
	}
	if !haveTarget {
		return errors.New("expected ':' in depfile")
	}
	return nil
}