336 lines
7.2 KiB
Go
336 lines
7.2 KiB
Go
// Copyright (c) 2017 Couchbase, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package regexp
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import (
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"regexp/syntax"
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"unicode"
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unicode_utf8 "unicode/utf8"
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"github.com/couchbase/vellum/utf8"
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)
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type compiler struct {
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sizeLimit uint
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insts prog
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instsPool []inst
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sequences utf8.Sequences
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rangeStack utf8.RangeStack
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startBytes []byte
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endBytes []byte
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}
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func newCompiler(sizeLimit uint) *compiler {
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return &compiler{
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sizeLimit: sizeLimit,
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startBytes: make([]byte, unicode_utf8.UTFMax),
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endBytes: make([]byte, unicode_utf8.UTFMax),
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}
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}
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func (c *compiler) compile(ast *syntax.Regexp) (prog, error) {
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err := c.c(ast)
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if err != nil {
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return nil, err
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}
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inst := c.allocInst()
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inst.op = OpMatch
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c.insts = append(c.insts, inst)
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return c.insts, nil
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}
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func (c *compiler) c(ast *syntax.Regexp) (err error) {
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if ast.Flags&syntax.NonGreedy > 1 {
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return ErrNoLazy
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}
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switch ast.Op {
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case syntax.OpEndLine, syntax.OpBeginLine,
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syntax.OpBeginText, syntax.OpEndText:
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return ErrNoEmpty
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case syntax.OpWordBoundary, syntax.OpNoWordBoundary:
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return ErrNoWordBoundary
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case syntax.OpEmptyMatch:
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return nil
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case syntax.OpLiteral:
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for _, r := range ast.Rune {
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if ast.Flags&syntax.FoldCase > 0 {
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next := syntax.Regexp{
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Op: syntax.OpCharClass,
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Flags: ast.Flags & syntax.FoldCase,
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Rune0: [2]rune{r, r},
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}
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next.Rune = next.Rune0[0:2]
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return c.c(&next)
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}
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c.sequences, c.rangeStack, err = utf8.NewSequencesPrealloc(
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r, r, c.sequences, c.rangeStack, c.startBytes, c.endBytes)
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if err != nil {
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return err
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}
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for _, seq := range c.sequences {
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c.compileUtf8Ranges(seq)
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}
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}
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case syntax.OpAnyChar:
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next := syntax.Regexp{
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Op: syntax.OpCharClass,
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Flags: ast.Flags & syntax.FoldCase,
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Rune0: [2]rune{0, unicode.MaxRune},
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}
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next.Rune = next.Rune0[:2]
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return c.c(&next)
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case syntax.OpAnyCharNotNL:
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next := syntax.Regexp{
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Op: syntax.OpCharClass,
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Flags: ast.Flags & syntax.FoldCase,
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Rune: []rune{0, 0x09, 0x0B, unicode.MaxRune},
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}
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return c.c(&next)
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case syntax.OpCharClass:
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return c.compileClass(ast)
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case syntax.OpCapture:
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return c.c(ast.Sub[0])
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case syntax.OpConcat:
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for _, sub := range ast.Sub {
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err := c.c(sub)
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if err != nil {
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return err
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}
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}
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return nil
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case syntax.OpAlternate:
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if len(ast.Sub) == 0 {
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return nil
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}
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jmpsToEnd := make([]uint, 0, len(ast.Sub)-1)
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// does not handle last entry
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for i := 0; i < len(ast.Sub)-1; i++ {
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sub := ast.Sub[i]
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split := c.emptySplit()
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j1 := c.top()
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err := c.c(sub)
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if err != nil {
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return err
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}
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jmpsToEnd = append(jmpsToEnd, c.emptyJump())
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j2 := c.top()
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c.setSplit(split, j1, j2)
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}
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// handle last entry
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err := c.c(ast.Sub[len(ast.Sub)-1])
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if err != nil {
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return err
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}
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end := uint(len(c.insts))
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for _, jmpToEnd := range jmpsToEnd {
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c.setJump(jmpToEnd, end)
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}
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case syntax.OpQuest:
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split := c.emptySplit()
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j1 := c.top()
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err := c.c(ast.Sub[0])
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if err != nil {
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return err
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}
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j2 := c.top()
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c.setSplit(split, j1, j2)
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case syntax.OpStar:
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j1 := c.top()
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split := c.emptySplit()
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j2 := c.top()
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err := c.c(ast.Sub[0])
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if err != nil {
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return err
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}
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jmp := c.emptyJump()
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j3 := uint(len(c.insts))
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c.setJump(jmp, j1)
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c.setSplit(split, j2, j3)
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case syntax.OpPlus:
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j1 := c.top()
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err := c.c(ast.Sub[0])
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if err != nil {
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return err
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}
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split := c.emptySplit()
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j2 := c.top()
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c.setSplit(split, j1, j2)
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case syntax.OpRepeat:
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if ast.Max == -1 {
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for i := 0; i < ast.Min; i++ {
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err := c.c(ast.Sub[0])
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if err != nil {
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return err
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}
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}
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next := syntax.Regexp{
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Op: syntax.OpStar,
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Flags: ast.Flags,
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Sub: ast.Sub,
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Sub0: ast.Sub0,
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Rune: ast.Rune,
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Rune0: ast.Rune0,
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}
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return c.c(&next)
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}
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for i := 0; i < ast.Min; i++ {
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err := c.c(ast.Sub[0])
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if err != nil {
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return err
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}
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}
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splits := make([]uint, 0, ast.Max-ast.Min)
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starts := make([]uint, 0, ast.Max-ast.Min)
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for i := ast.Min; i < ast.Max; i++ {
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splits = append(splits, c.emptySplit())
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starts = append(starts, uint(len(c.insts)))
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err := c.c(ast.Sub[0])
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if err != nil {
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return err
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}
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}
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end := uint(len(c.insts))
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for i := 0; i < len(splits); i++ {
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c.setSplit(splits[i], starts[i], end)
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}
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}
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return c.checkSize()
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}
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func (c *compiler) checkSize() error {
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if uint(len(c.insts)*instSize) > c.sizeLimit {
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return ErrCompiledTooBig
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}
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return nil
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}
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func (c *compiler) compileClass(ast *syntax.Regexp) error {
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if len(ast.Rune) == 0 {
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return nil
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}
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jmps := make([]uint, 0, len(ast.Rune)-2)
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// does not do last pair
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for i := 0; i < len(ast.Rune)-2; i += 2 {
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rstart := ast.Rune[i]
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rend := ast.Rune[i+1]
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split := c.emptySplit()
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j1 := c.top()
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err := c.compileClassRange(rstart, rend)
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if err != nil {
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return err
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}
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jmps = append(jmps, c.emptyJump())
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j2 := c.top()
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c.setSplit(split, j1, j2)
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}
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// handle last pair
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rstart := ast.Rune[len(ast.Rune)-2]
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rend := ast.Rune[len(ast.Rune)-1]
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err := c.compileClassRange(rstart, rend)
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if err != nil {
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return err
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}
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end := c.top()
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for _, jmp := range jmps {
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c.setJump(jmp, end)
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}
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return nil
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}
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func (c *compiler) compileClassRange(startR, endR rune) (err error) {
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c.sequences, c.rangeStack, err = utf8.NewSequencesPrealloc(
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startR, endR, c.sequences, c.rangeStack, c.startBytes, c.endBytes)
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if err != nil {
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return err
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}
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jmps := make([]uint, 0, len(c.sequences)-1)
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// does not do last entry
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for i := 0; i < len(c.sequences)-1; i++ {
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seq := c.sequences[i]
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split := c.emptySplit()
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j1 := c.top()
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c.compileUtf8Ranges(seq)
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jmps = append(jmps, c.emptyJump())
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j2 := c.top()
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c.setSplit(split, j1, j2)
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}
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// handle last entry
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c.compileUtf8Ranges(c.sequences[len(c.sequences)-1])
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end := c.top()
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for _, jmp := range jmps {
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c.setJump(jmp, end)
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}
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return nil
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}
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func (c *compiler) compileUtf8Ranges(seq utf8.Sequence) {
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for _, r := range seq {
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inst := c.allocInst()
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inst.op = OpRange
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inst.rangeStart = r.Start
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inst.rangeEnd = r.End
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c.insts = append(c.insts, inst)
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}
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}
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func (c *compiler) emptySplit() uint {
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inst := c.allocInst()
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inst.op = OpSplit
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c.insts = append(c.insts, inst)
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return c.top() - 1
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}
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func (c *compiler) emptyJump() uint {
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inst := c.allocInst()
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inst.op = OpJmp
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c.insts = append(c.insts, inst)
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return c.top() - 1
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}
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func (c *compiler) setSplit(i, pc1, pc2 uint) {
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split := c.insts[i]
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split.splitA = pc1
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split.splitB = pc2
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}
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func (c *compiler) setJump(i, pc uint) {
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jmp := c.insts[i]
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jmp.to = pc
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}
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func (c *compiler) top() uint {
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return uint(len(c.insts))
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}
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func (c *compiler) allocInst() *inst {
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if len(c.instsPool) <= 0 {
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c.instsPool = make([]inst, 16)
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}
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inst := &c.instsPool[0]
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c.instsPool = c.instsPool[1:]
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return inst
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}
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