mirror of
https://github.com/golang/go
synced 2024-11-22 02:44:39 -07:00
exp/regexp/syntax: syntax data structures, parser
Parser is a work in progress but can populate most of the interesting parts of the data structure, so a good checkpoint. All the complicated Perl syntax is missing, as are various important optimizations made during parsing to the syntax tree. The plan is that exp/regexp's API will mimic regexp, and exp/regexp/syntax provides the parser directly for programs that need it (and for implementing exp/regexp). Once finished, exp/regexp will replace regexp. R=r, sam.thorogood, kevlar, edsrzf CC=golang-dev https://golang.org/cl/4538123
This commit is contained in:
Russ Cox
parent
b4bb970e18
commit
b96c3477f8
@ -81,6 +81,7 @@ DIRS=\
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exp/eval\
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exp/gui\
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exp/gui/x11\
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exp/regexp/syntax\
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expvar\
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flag\
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fmt\
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12
src/pkg/exp/regexp/syntax/Makefile
Normal file
12
src/pkg/exp/regexp/syntax/Makefile
Normal file
@ -0,0 +1,12 @@
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# Copyright 2011 The Go Authors. All rights reserved.
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# Use of this source code is governed by a BSD-style
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# license that can be found in the LICENSE file.
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include ../../../../Make.inc
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TARG=exp/regexp/syntax
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GOFILES=\
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parse.go\
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regexp.go\
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include ../../../../Make.pkg
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561
src/pkg/exp/regexp/syntax/parse.go
Normal file
561
src/pkg/exp/regexp/syntax/parse.go
Normal file
@ -0,0 +1,561 @@
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// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package syntax
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import (
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"os"
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"sort"
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"unicode"
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"utf8"
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)
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// An Error describes a failure to parse a regular expression
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// and gives the offending expression.
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type Error struct {
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Code ErrorCode
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Expr string
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}
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func (e *Error) String() string {
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return "error parsing regexp: " + e.Code.String() + ": `" + e.Expr + "`"
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}
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// An ErrorCode describes a failure to parse a regular expression.
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type ErrorCode string
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const (
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// Unexpected error
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ErrInternalError ErrorCode = "regexp/syntax: internal error"
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// Parse errors
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ErrInvalidCharClass ErrorCode = "invalid character class"
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ErrInvalidCharRange ErrorCode = "invalid character class range"
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ErrInvalidEscape ErrorCode = "invalid escape sequence"
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ErrInvalidNamedCapture ErrorCode = "invalid named capture"
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ErrInvalidPerlOp ErrorCode = "invalid or unsupported Perl syntax"
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ErrInvalidRepeatOp ErrorCode = "invalid nested repetition operator"
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ErrInvalidRepeatSize ErrorCode = "invalid repeat count"
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ErrInvalidUTF8 ErrorCode = "invalid UTF-8"
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ErrMissingBracket ErrorCode = "missing closing ]"
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ErrMissingParen ErrorCode = "missing closing )"
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ErrMissingRepeatArgument ErrorCode = "missing argument to repetition operator"
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ErrTrailingBackslash ErrorCode = "trailing backslash at end of expression"
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)
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func (e ErrorCode) String() string {
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return string(e)
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}
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// Flags control the behavior of the parser and record information about regexp context.
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type Flags uint16
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const (
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FoldCase Flags = 1 << iota // case-insensitive match
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Literal // treat pattern as literal string
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ClassNL // allow character classes like [^a-z] and [[:space:]] to match newline
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DotNL // allow . to match newline
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OneLine // treat ^ and $ as only matching at beginning and end of text
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NonGreedy // make repetition operators default to non-greedy
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PerlX // allow Perl extensions
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UnicodeGroups // allow \p{Han}, \P{Han} for Unicode group and negation
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WasDollar // regexp OpEndText was $, not \z
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Simple // regexp contains no counted repetition
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MatchNL = ClassNL | DotNL
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Perl = ClassNL | OneLine | PerlX | UnicodeGroups // as close to Perl as possible
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POSIX Flags = 0 // POSIX syntax
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)
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// Pseudo-ops for parsing stack.
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const (
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opLeftParen = opPseudo + iota
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opVerticalBar
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)
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type parser struct {
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flags Flags // parse mode flags
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stack []*Regexp // stack of parsed expressions
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numCap int // number of capturing groups seen
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wholeRegexp string
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}
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// Parse stack manipulation.
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// push pushes the regexp re onto the parse stack and returns the regexp.
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func (p *parser) push(re *Regexp) *Regexp {
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// TODO: automatic concatenation
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// TODO: turn character class into literal
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// TODO: compute simple
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p.stack = append(p.stack, re)
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return re
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}
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// newLiteral returns a new OpLiteral Regexp with the given flags
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func newLiteral(r int, flags Flags) *Regexp {
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re := &Regexp{
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Op: OpLiteral,
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Flags: flags,
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}
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re.Rune0[0] = r
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re.Rune = re.Rune0[:1]
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return re
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}
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// literal pushes a literal regexp for the rune r on the stack
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// and returns that regexp.
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func (p *parser) literal(r int) *Regexp {
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return p.push(newLiteral(r, p.flags))
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}
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// op pushes a regexp with the given op onto the stack
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// and returns that regexp.
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func (p *parser) op(op Op) *Regexp {
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return p.push(&Regexp{Op: op, Flags: p.flags})
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}
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// repeat replaces the top stack element with itself repeated
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// according to op.
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func (p *parser) repeat(op Op, opstr string) os.Error {
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n := len(p.stack)
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if n == 0 {
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return &Error{ErrMissingRepeatArgument, opstr}
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}
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sub := p.stack[n-1]
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re := &Regexp{
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Op: op,
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}
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re.Sub = re.Sub0[:1]
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re.Sub[0] = sub
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p.stack[n-1] = re
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return nil
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}
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// concat replaces the top of the stack (above the topmost '|' or '(') with its concatenation.
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func (p *parser) concat() *Regexp {
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// TODO: Flatten concats.
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// Scan down to find pseudo-operator | or (.
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i := len(p.stack)
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for i > 0 && p.stack[i-1].Op < opPseudo {
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i--
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}
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sub := p.stack[i:]
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p.stack = p.stack[:i]
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var re *Regexp
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switch len(sub) {
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case 0:
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re = &Regexp{Op: OpEmptyMatch}
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case 1:
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re = sub[0]
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default:
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re = &Regexp{Op: OpConcat}
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re.Sub = append(re.Sub0[:0], sub...)
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}
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return p.push(re)
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}
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// alternate replaces the top of the stack (above the topmost '(') with its alternation.
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func (p *parser) alternate() *Regexp {
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// TODO: Flatten alternates.
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// Scan down to find pseudo-operator (.
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// There are no | above (.
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i := len(p.stack)
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for i > 0 && p.stack[i-1].Op < opPseudo {
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i--
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}
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sub := p.stack[i:]
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p.stack = p.stack[:i]
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var re *Regexp
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switch len(sub) {
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case 0:
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re = &Regexp{Op: OpNoMatch}
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case 1:
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re = sub[0]
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default:
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re = &Regexp{Op: OpAlternate}
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re.Sub = append(re.Sub0[:0], sub...)
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}
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return p.push(re)
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}
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// Parsing.
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func Parse(s string, flags Flags) (*Regexp, os.Error) {
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if flags&Literal != 0 {
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// Trivial parser for literal string.
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if err := checkUTF8(s); err != nil {
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return nil, err
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}
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re := &Regexp{
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Op: OpLiteral,
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Flags: flags,
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}
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re.Rune = re.Rune0[:0] // use local storage for small strings
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for _, c := range s {
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if len(re.Rune) >= cap(re.Rune) {
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// string is too long to fit in Rune0. let Go handle it
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re.Rune = []int(s)
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break
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}
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re.Rune = append(re.Rune, c)
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}
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return re, nil
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}
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// Otherwise, must do real work.
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var (
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p parser
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err os.Error
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c int
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op Op
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)
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p.flags = flags
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p.wholeRegexp = s
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t := s
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for t != "" {
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switch t[0] {
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default:
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if c, t, err = nextRune(t); err != nil {
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return nil, err
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}
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p.literal(c)
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case '(':
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// TODO: Actual Perl flag parsing.
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if len(t) >= 3 && t[1] == '?' && t[2] == ':' {
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// non-capturing paren
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p.op(opLeftParen)
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t = t[3:]
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break
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}
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p.numCap++
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p.op(opLeftParen).Cap = p.numCap
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t = t[1:]
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case '|':
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p.concat()
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if err = p.parseVerticalBar(); err != nil {
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return nil, err
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}
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t = t[1:]
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case ')':
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if err = p.parseRightParen(); err != nil {
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return nil, err
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}
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t = t[1:]
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case '^':
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if p.flags&OneLine != 0 {
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p.op(OpBeginText)
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} else {
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p.op(OpBeginLine)
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}
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t = t[1:]
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case '$':
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if p.flags&OneLine != 0 {
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p.op(OpEndText).Flags |= WasDollar
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} else {
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p.op(OpEndLine)
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}
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t = t[1:]
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case '.':
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if p.flags&DotNL != 0 {
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p.op(OpAnyChar)
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} else {
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p.op(OpAnyCharNotNL)
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}
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t = t[1:]
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case '[':
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if t, err = p.parseClass(t); err != nil {
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return nil, err
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}
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case '*', '+', '?':
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switch t[0] {
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case '*':
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op = OpStar
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case '+':
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op = OpPlus
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case '?':
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op = OpQuest
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}
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// TODO: greedy
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if err = p.repeat(op, t[0:1]); err != nil {
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return nil, err
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}
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t = t[1:]
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case '{':
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return nil, os.NewError("repeat not implemented")
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case '\\':
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return nil, os.NewError("escape not implemented")
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}
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}
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p.concat()
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if p.swapVerticalBar() {
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// pop vertical bar
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p.stack = p.stack[:len(p.stack)-1]
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}
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p.alternate()
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n := len(p.stack)
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if n != 1 {
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return nil, &Error{ErrMissingParen, s}
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}
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return p.stack[0], nil
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}
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// parseVerticalBar handles a | in the input.
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func (p *parser) parseVerticalBar() os.Error {
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p.concat()
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// The concatenation we just parsed is on top of the stack.
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// If it sits above an opVerticalBar, swap it below
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// (things below an opVerticalBar become an alternation).
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// Otherwise, push a new vertical bar.
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if !p.swapVerticalBar() {
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p.op(opVerticalBar)
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}
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return nil
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}
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// If the top of the stack is an element followed by an opVerticalBar
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// swapVerticalBar swaps the two and returns true.
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// Otherwise it returns false.
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func (p *parser) swapVerticalBar() bool {
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if n := len(p.stack); n >= 2 {
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re1 := p.stack[n-1]
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re2 := p.stack[n-2]
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if re2.Op == opVerticalBar {
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p.stack[n-2] = re1
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p.stack[n-1] = re2
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return true
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}
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}
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return false
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}
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// parseRightParen handles a ) in the input.
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func (p *parser) parseRightParen() os.Error {
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p.concat()
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if p.swapVerticalBar() {
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// pop vertical bar
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p.stack = p.stack[:len(p.stack)-1]
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}
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p.alternate()
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n := len(p.stack)
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if n < 2 {
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return &Error{ErrInternalError, ""}
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}
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re1 := p.stack[n-1]
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re2 := p.stack[n-2]
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p.stack = p.stack[:n-2]
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if re2.Op != opLeftParen {
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return &Error{ErrMissingParen, p.wholeRegexp}
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}
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if re2.Cap == 0 {
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// Just for grouping.
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p.push(re1)
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} else {
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re2.Op = OpCapture
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re2.Sub = re2.Sub0[:1]
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re2.Sub[0] = re1
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p.push(re2)
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}
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return nil
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}
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// parseClassChar parses a character class character at the beginning of s
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// and returns it.
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func (p *parser) parseClassChar(s, wholeClass string) (r int, rest string, err os.Error) {
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if s == "" {
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return 0, "", &Error{Code: ErrMissingBracket, Expr: wholeClass}
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}
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// TODO: Escapes
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return nextRune(s)
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}
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// parseClass parses a character class at the beginning of s
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// and pushes it onto the parse stack.
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func (p *parser) parseClass(s string) (rest string, err os.Error) {
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t := s[1:] // chop [
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re := &Regexp{Op: OpCharClass, Flags: p.flags}
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re.Rune = re.Rune0[:0]
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sign := +1
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if t != "" && t[0] == '^' {
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sign = -1
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t = t[1:]
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// If character class does not match \n, add it here,
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// so that negation later will do the right thing.
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if p.flags&ClassNL == 0 {
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re.Rune = append(re.Rune, '\n', '\n')
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}
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}
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class := re.Rune
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first := true // ] and - are okay as first char in class
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for t == "" || t[0] != ']' || first {
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// POSIX: - is only okay unescaped as first or last in class.
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// Perl: - is okay anywhere.
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if t != "" && t[0] == '-' && p.flags&PerlX == 0 && !first && (len(t) == 1 || t[1] != ']') {
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_, size := utf8.DecodeRuneInString(t[1:])
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return "", &Error{Code: ErrInvalidCharRange, Expr: t[:1+size]}
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}
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first = false
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// TODO: Look for [:alnum:]
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// TODO: Look for Unicode group.
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// TODO: Look for Perl group.
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// Single character or simple range.
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rng := t
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var lo, hi int
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if lo, t, err = p.parseClassChar(t, s); err != nil {
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return "", err
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}
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hi = lo
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// [a-] means (a|-) so check for final ].
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if len(t) >= 2 && t[0] == '-' && t[1] != ']' {
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t = t[1:]
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if hi, t, err = p.parseClassChar(t, s); err != nil {
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return "", err
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}
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if hi < lo {
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rng = rng[:len(rng)-len(t)]
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return "", &Error{Code: ErrInvalidCharRange, Expr: rng}
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}
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}
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// Expand last range if overlaps or abuts.
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if n := len(class); n > 0 {
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clo, chi := class[n-2], class[n-1]
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if lo <= chi+1 && clo <= hi+1 {
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if lo < clo {
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class[n-2] = lo
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}
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if hi > chi {
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class[n-1] = hi
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}
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continue
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}
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}
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class = append(class, lo, hi)
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}
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t = t[1:] // chop ]
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// Use &re.Rune instead of &class to avoid allocation.
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re.Rune = class
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class = cleanClass(&re.Rune)
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if sign < 0 {
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class = negateClass(class)
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}
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re.Rune = class
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p.push(re)
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return t, nil
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}
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// cleanClass sorts the ranges (pairs of elements of r),
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// merges them, and eliminates duplicates.
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func cleanClass(rp *[]int) []int {
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// Sort by lo increasing, hi decreasing to break ties.
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sort.Sort(ranges{rp})
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r := *rp
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// Merge abutting, overlapping.
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w := 2 // write index
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for i := 2; i < len(r); i += 2 {
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lo, hi := r[i], r[i+1]
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if lo <= r[w-1]+1 {
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// merge with previous range
|
||||
if hi > r[w-1] {
|
||||
r[w-1] = hi
|
||||
}
|
||||
continue
|
||||
}
|
||||
// new disjoint range
|
||||
r[w] = lo
|
||||
r[w+1] = hi
|
||||
w += 2
|
||||
}
|
||||
|
||||
return r[:w]
|
||||
}
|
||||
|
||||
// negateClass overwrites r and returns r's negation.
|
||||
// It assumes the class r is already clean.
|
||||
func negateClass(r []int) []int {
|
||||
nextLo := 0 // lo end of next class to add
|
||||
w := 0 // write index
|
||||
for i := 0; i < len(r); i += 2 {
|
||||
lo, hi := r[i], r[i+1]
|
||||
if nextLo <= lo-1 {
|
||||
r[w] = nextLo
|
||||
r[w+1] = lo - 1
|
||||
w += 2
|
||||
}
|
||||
nextLo = hi + 1
|
||||
}
|
||||
if nextLo <= unicode.MaxRune {
|
||||
// It's possible for the negation to have one more
|
||||
// range - this one - than the original class, so use append.
|
||||
r = append(r[:w], nextLo, unicode.MaxRune)
|
||||
}
|
||||
return r
|
||||
}
|
||||
|
||||
// ranges implements sort.Interface on a []rune.
|
||||
// The choice of receiver type definition is strange
|
||||
// but avoids an allocation since we already have
|
||||
// a *[]int.
|
||||
type ranges struct {
|
||||
p *[]int
|
||||
}
|
||||
|
||||
func (ra ranges) Less(i, j int) bool {
|
||||
p := *ra.p
|
||||
i *= 2
|
||||
j *= 2
|
||||
return p[i] < p[j] || p[i] == p[j] && p[i+1] > p[j+1]
|
||||
}
|
||||
|
||||
func (ra ranges) Len() int {
|
||||
return len(*ra.p) / 2
|
||||
}
|
||||
|
||||
func (ra ranges) Swap(i, j int) {
|
||||
p := *ra.p
|
||||
i *= 2
|
||||
j *= 2
|
||||
p[i], p[i+1], p[j], p[j+1] = p[j], p[j+1], p[i], p[i+1]
|
||||
}
|
||||
|
||||
|
||||
func checkUTF8(s string) os.Error {
|
||||
for s != "" {
|
||||
rune, size := utf8.DecodeRuneInString(s)
|
||||
if rune == utf8.RuneError && size == 1 {
|
||||
return &Error{Code: ErrInvalidUTF8, Expr: s}
|
||||
}
|
||||
s = s[size:]
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
func nextRune(s string) (c int, t string, err os.Error) {
|
||||
c, size := utf8.DecodeRuneInString(s)
|
||||
if c == utf8.RuneError && size == 1 {
|
||||
return 0, "", &Error{Code: ErrInvalidUTF8, Expr: s}
|
||||
}
|
||||
return c, s[size:], nil
|
||||
}
|
||||
266
src/pkg/exp/regexp/syntax/parse_test.go
Normal file
266
src/pkg/exp/regexp/syntax/parse_test.go
Normal file
@ -0,0 +1,266 @@
|
||||
// Copyright 2011 The Go Authors. All rights reserved.
|
||||
// Use of this source code is governed by a BSD-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
package syntax
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"fmt"
|
||||
"testing"
|
||||
"unicode"
|
||||
)
|
||||
|
||||
var parseTests = []struct {
|
||||
Regexp string
|
||||
Dump string
|
||||
}{
|
||||
// Base cases
|
||||
{"a", "lit{a}"},
|
||||
{"a.", "cat{lit{a}dot{}}"},
|
||||
{"a.b", "cat{lit{a}dot{}lit{b}}"},
|
||||
// { "ab", "str{ab}" },
|
||||
{"ab", "cat{lit{a}lit{b}}"},
|
||||
{"a.b.c", "cat{lit{a}dot{}lit{b}dot{}lit{c}}"},
|
||||
// { "abc", "str{abc}" },
|
||||
{"abc", "cat{lit{a}lit{b}lit{c}}"},
|
||||
{"a|^", "alt{lit{a}bol{}}"},
|
||||
// { "a|b", "cc{0x61-0x62}" },
|
||||
{"a|b", "alt{lit{a}lit{b}}"},
|
||||
{"(a)", "cap{lit{a}}"},
|
||||
{"(a)|b", "alt{cap{lit{a}}lit{b}}"},
|
||||
{"a*", "star{lit{a}}"},
|
||||
{"a+", "plus{lit{a}}"},
|
||||
{"a?", "que{lit{a}}"},
|
||||
// { "a{2}", "rep{2,2 lit{a}}" },
|
||||
// { "a{2,3}", "rep{2,3 lit{a}}" },
|
||||
// { "a{2,}", "rep{2,-1 lit{a}}" },
|
||||
// { "a*?", "nstar{lit{a}}" },
|
||||
// { "a+?", "nplus{lit{a}}" },
|
||||
// { "a??", "nque{lit{a}}" },
|
||||
// { "a{2}?", "nrep{2,2 lit{a}}" },
|
||||
// { "a{2,3}?", "nrep{2,3 lit{a}}" },
|
||||
// { "a{2,}?", "nrep{2,-1 lit{a}}" },
|
||||
{"", "emp{}"},
|
||||
// { "|", "emp{}" }, // alt{emp{}emp{}} but got factored
|
||||
// { "|", "alt{emp{}emp{}}" },
|
||||
{"|x|", "alt{emp{}lit{x}emp{}}"},
|
||||
{".", "dot{}"},
|
||||
{"^", "bol{}"},
|
||||
{"$", "eol{}"},
|
||||
// { "\\|", "lit{|}" },
|
||||
// { "\\(", "lit{(}" },
|
||||
// { "\\)", "lit{)}" },
|
||||
// { "\\*", "lit{*}" },
|
||||
// { "\\+", "lit{+}" },
|
||||
// { "\\?", "lit{?}" },
|
||||
// { "{", "lit{{}" },
|
||||
{"}", "lit{}}"},
|
||||
// { "\\.", "lit{.}" },
|
||||
// { "\\^", "lit{^}" },
|
||||
// { "\\$", "lit{$}" },
|
||||
// { "\\\\", "lit{\\}" },
|
||||
{"[ace]", "cc{0x61 0x63 0x65}"},
|
||||
{"[abc]", "cc{0x61-0x63}"},
|
||||
{"[a-z]", "cc{0x61-0x7a}"},
|
||||
// { "[a]", "lit{a}" },
|
||||
{"[a]", "cc{0x61}"},
|
||||
// { "\\-", "lit{-}" },
|
||||
{"-", "lit{-}"},
|
||||
// { "\\_", "lit{_}" },
|
||||
|
||||
// Posix and Perl extensions
|
||||
// { "[[:lower:]]", "cc{0x61-0x7a}" },
|
||||
// { "[a-z]", "cc{0x61-0x7a}" },
|
||||
// { "[^[:lower:]]", "cc{0x0-0x60 0x7b-0x10ffff}" },
|
||||
// { "[[:^lower:]]", "cc{0x0-0x60 0x7b-0x10ffff}" },
|
||||
// { "(?i)[[:lower:]]", "cc{0x41-0x5a 0x61-0x7a 0x17f 0x212a}" },
|
||||
// { "(?i)[a-z]", "cc{0x41-0x5a 0x61-0x7a 0x17f 0x212a}" },
|
||||
// { "(?i)[^[:lower:]]", "cc{0x0-0x40 0x5b-0x60 0x7b-0x17e 0x180-0x2129 0x212b-0x10ffff}" },
|
||||
// { "(?i)[[:^lower:]]", "cc{0x0-0x40 0x5b-0x60 0x7b-0x17e 0x180-0x2129 0x212b-0x10ffff}" },
|
||||
// { "\\d", "cc{0x30-0x39}" },
|
||||
// { "\\D", "cc{0x0-0x2f 0x3a-0x10ffff}" },
|
||||
// { "\\s", "cc{0x9-0xa 0xc-0xd 0x20}" },
|
||||
// { "\\S", "cc{0x0-0x8 0xb 0xe-0x1f 0x21-0x10ffff}" },
|
||||
// { "\\w", "cc{0x30-0x39 0x41-0x5a 0x5f 0x61-0x7a}" },
|
||||
// { "\\W", "cc{0x0-0x2f 0x3a-0x40 0x5b-0x5e 0x60 0x7b-0x10ffff}" },
|
||||
// { "(?i)\\w", "cc{0x30-0x39 0x41-0x5a 0x5f 0x61-0x7a 0x17f 0x212a}" },
|
||||
// { "(?i)\\W", "cc{0x0-0x2f 0x3a-0x40 0x5b-0x5e 0x60 0x7b-0x17e 0x180-0x2129 0x212b-0x10ffff}" },
|
||||
// { "[^\\\\]", "cc{0x0-0x5b 0x5d-0x10ffff}" },
|
||||
// { "\\C", "byte{}" },
|
||||
|
||||
// Unicode, negatives, and a double negative.
|
||||
// { "\\p{Braille}", "cc{0x2800-0x28ff}" },
|
||||
// { "\\P{Braille}", "cc{0x0-0x27ff 0x2900-0x10ffff}" },
|
||||
// { "\\p{^Braille}", "cc{0x0-0x27ff 0x2900-0x10ffff}" },
|
||||
// { "\\P{^Braille}", "cc{0x2800-0x28ff}" },
|
||||
|
||||
// More interesting regular expressions.
|
||||
// { "a{,2}", "str{a{,2}}" },
|
||||
// { "\\.\\^\\$\\\\", "str{.^$\\}" },
|
||||
{"[a-zABC]", "cc{0x41-0x43 0x61-0x7a}"},
|
||||
{"[^a]", "cc{0x0-0x60 0x62-0x10ffff}"},
|
||||
{"[\xce\xb1-\xce\xb5\xe2\x98\xba]", "cc{0x3b1-0x3b5 0x263a}"}, // utf-8
|
||||
// { "a*{", "cat{star{lit{a}}lit{{}}" },
|
||||
|
||||
// Test precedences
|
||||
// { "(?:ab)*", "star{str{ab}}" },
|
||||
// { "(ab)*", "star{cap{str{ab}}}" },
|
||||
// { "ab|cd", "alt{str{ab}str{cd}}" },
|
||||
// { "a(b|c)d", "cat{lit{a}cap{cc{0x62-0x63}}lit{d}}" },
|
||||
{"(?:ab)*", "star{cat{lit{a}lit{b}}}"},
|
||||
{"(ab)*", "star{cap{cat{lit{a}lit{b}}}}"},
|
||||
{"ab|cd", "alt{cat{lit{a}lit{b}}cat{lit{c}lit{d}}}"},
|
||||
{"a(b|c)d", "cat{lit{a}cap{alt{lit{b}lit{c}}}lit{d}}"},
|
||||
|
||||
// Test flattening.
|
||||
// { "(?:a)", "lit{a}" },
|
||||
// { "(?:ab)(?:cd)", "str{abcd}" },
|
||||
// { "(?:a|b)|(?:c|d)", "cc{0x61-0x64}" },
|
||||
// { "a|.", "dot{}" },
|
||||
// { ".|a", "dot{}" },
|
||||
|
||||
// Test Perl quoted literals
|
||||
// { "\\Q+|*?{[\\E", "str{+|*?{[}" },
|
||||
// { "\\Q+\\E+", "plus{lit{+}}" },
|
||||
// { "\\Q\\\\E", "lit{\\}" },
|
||||
// { "\\Q\\\\\\E", "str{\\\\}" },
|
||||
|
||||
// Test Perl \A and \z
|
||||
// { "(?m)^", "bol{}" },
|
||||
// { "(?m)$", "eol{}" },
|
||||
// { "(?-m)^", "bot{}" },
|
||||
// { "(?-m)$", "eot{}" },
|
||||
// { "(?m)\\A", "bot{}" },
|
||||
// { "(?m)\\z", "eot{\\z}" },
|
||||
// { "(?-m)\\A", "bot{}" },
|
||||
// { "(?-m)\\z", "eot{\\z}" },
|
||||
|
||||
// Test named captures
|
||||
// { "(?P<name>a)", "cap{name:lit{a}}" },
|
||||
|
||||
// Case-folded literals
|
||||
// { "[Aa]", "litfold{a}" },
|
||||
|
||||
// Strings
|
||||
// { "abcde", "str{abcde}" },
|
||||
// { "[Aa][Bb]cd", "cat{strfold{ab}str{cd}}" },
|
||||
}
|
||||
|
||||
const testFlags = MatchNL | PerlX | UnicodeGroups
|
||||
|
||||
// Test Parse -> Dump.
|
||||
func TestParseDump(t *testing.T) {
|
||||
for _, tt := range parseTests {
|
||||
re, err := Parse(tt.Regexp, testFlags)
|
||||
if err != nil {
|
||||
t.Errorf("Parse(%#q): %v", tt.Regexp, err)
|
||||
continue
|
||||
}
|
||||
d := dump(re)
|
||||
if d != tt.Dump {
|
||||
t.Errorf("Parse(%#q).Dump() = %#q want %#q", tt.Regexp, d, tt.Dump)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// dump prints a string representation of the regexp showing
|
||||
// the structure explicitly.
|
||||
func dump(re *Regexp) string {
|
||||
var b bytes.Buffer
|
||||
dumpRegexp(&b, re)
|
||||
return b.String()
|
||||
}
|
||||
|
||||
var opNames = []string{
|
||||
OpNoMatch: "no",
|
||||
OpEmptyMatch: "emp",
|
||||
OpLiteral: "lit",
|
||||
OpCharClass: "cc",
|
||||
OpAnyCharNotNL: "dnl",
|
||||
OpAnyChar: "dot",
|
||||
OpBeginLine: "bol",
|
||||
OpEndLine: "eol",
|
||||
OpBeginText: "bot",
|
||||
OpEndText: "eot",
|
||||
OpWordBoundary: "wb",
|
||||
OpNoWordBoundary: "nwb",
|
||||
OpCapture: "cap",
|
||||
OpStar: "star",
|
||||
OpPlus: "plus",
|
||||
OpQuest: "que",
|
||||
OpRepeat: "rep",
|
||||
OpConcat: "cat",
|
||||
OpAlternate: "alt",
|
||||
}
|
||||
|
||||
// dumpRegexp writes an encoding of the syntax tree for the regexp re to b.
|
||||
// It is used during testing to distinguish between parses that might print
|
||||
// the same using re's String method.
|
||||
func dumpRegexp(b *bytes.Buffer, re *Regexp) {
|
||||
if int(re.Op) >= len(opNames) || opNames[re.Op] == "" {
|
||||
fmt.Fprintf(b, "op%d", re.Op)
|
||||
} else {
|
||||
switch re.Op {
|
||||
default:
|
||||
b.WriteString(opNames[re.Op])
|
||||
case OpStar, OpPlus, OpQuest, OpRepeat:
|
||||
if re.Flags&NonGreedy != 0 {
|
||||
b.WriteByte('n')
|
||||
}
|
||||
b.WriteString(opNames[re.Op])
|
||||
case OpLiteral:
|
||||
if len(re.Rune) > 1 {
|
||||
b.WriteString("str")
|
||||
} else {
|
||||
b.WriteString("lit")
|
||||
}
|
||||
if re.Flags&FoldCase != 0 {
|
||||
for _, r := range re.Rune {
|
||||
if unicode.ToUpper(r) != r {
|
||||
b.WriteString("fold")
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
b.WriteByte('{')
|
||||
switch re.Op {
|
||||
case OpEndText:
|
||||
if re.Flags&WasDollar == 0 {
|
||||
b.WriteString(`\z`)
|
||||
}
|
||||
case OpLiteral:
|
||||
for _, r := range re.Rune {
|
||||
b.WriteRune(r)
|
||||
}
|
||||
case OpConcat, OpAlternate:
|
||||
for _, sub := range re.Sub {
|
||||
dumpRegexp(b, sub)
|
||||
}
|
||||
case OpStar, OpPlus, OpQuest:
|
||||
dumpRegexp(b, re.Sub[0])
|
||||
case OpRepeat:
|
||||
fmt.Fprintf(b, "%d,%d ", re.Min, re.Max)
|
||||
dumpRegexp(b, re.Sub[0])
|
||||
case OpCapture:
|
||||
if re.Name != "" {
|
||||
b.WriteString(re.Name)
|
||||
b.WriteByte(':')
|
||||
}
|
||||
dumpRegexp(b, re.Sub[0])
|
||||
case OpCharClass:
|
||||
sep := ""
|
||||
for i := 0; i < len(re.Rune); i += 2 {
|
||||
b.WriteString(sep)
|
||||
sep = " "
|
||||
lo, hi := re.Rune[i], re.Rune[i+1]
|
||||
if lo == hi {
|
||||
fmt.Fprintf(b, "%#x", lo)
|
||||
} else {
|
||||
fmt.Fprintf(b, "%#x-%#x", lo, hi)
|
||||
}
|
||||
}
|
||||
}
|
||||
b.WriteByte('}')
|
||||
}
|
||||
210
src/pkg/exp/regexp/syntax/regexp.go
Normal file
210
src/pkg/exp/regexp/syntax/regexp.go
Normal file
@ -0,0 +1,210 @@
|
||||
// Copyright 2011 The Go Authors. All rights reserved.
|
||||
// Use of this source code is governed by a BSD-style
|
||||
// license that can be found in the LICENSE file.
|
||||
|
||||
// Package syntax parses regular expressions into syntax trees.
|
||||
// WORK IN PROGRESS.
|
||||
package syntax
|
||||
|
||||
// Note to implementers:
|
||||
// In this package, re is always a *Regexp and r is always a rune.
|
||||
|
||||
import (
|
||||
"bytes"
|
||||
"strconv"
|
||||
"strings"
|
||||
"unicode"
|
||||
)
|
||||
|
||||
// A Regexp is a node in a regular expression syntax tree.
|
||||
type Regexp struct {
|
||||
Op Op // operator
|
||||
Flags Flags
|
||||
Sub []*Regexp // subexpressions, if any
|
||||
Sub0 [1]*Regexp // storage for short Sub
|
||||
Rune []int // matched runes, for OpLiteral, OpCharClass
|
||||
Rune0 [2]int // storage for short Rune
|
||||
Min, Max int // min, max for OpRepeat
|
||||
Cap int // capturing index, for OpCapture
|
||||
Name string // capturing name, for OpCapture
|
||||
}
|
||||
|
||||
// An Op is a single regular expression operator.
|
||||
type Op uint8
|
||||
|
||||
// Operators are listed in precedence order, tightest binding to weakest.
|
||||
|
||||
const (
|
||||
OpNoMatch Op = 1 + iota // matches no strings
|
||||
OpEmptyMatch // matches empty string
|
||||
OpLiteral // matches Runes sequence
|
||||
OpCharClass // matches Runes interpreted as range pair list
|
||||
OpAnyCharNotNL // matches any character
|
||||
OpAnyChar // matches any character
|
||||
OpBeginLine // matches empty string at beginning of line
|
||||
OpEndLine // matches empty string at end of line
|
||||
OpBeginText // matches empty string at beginning of text
|
||||
OpEndText // matches empty string at end of text
|
||||
OpWordBoundary // matches word boundary `\b`
|
||||
OpNoWordBoundary // matches word non-boundary `\B`
|
||||
OpCapture // capturing subexpression with index Cap, optional name Name
|
||||
OpStar // matches Sub[0] zero or more times
|
||||
OpPlus // matches Sub[0] one or more times
|
||||
OpQuest // matches Sub[0] zero or one times
|
||||
OpRepeat // matches Sub[0] at least Min times, at most Max (Max == -1 is no limit)
|
||||
OpConcat // matches concatenation of Subs
|
||||
OpAlternate // matches alternation of Subs
|
||||
)
|
||||
|
||||
const opPseudo Op = 128 // where pseudo-ops start
|
||||
|
||||
// writeRegexp writes the Perl syntax for the regular expression re to b.
|
||||
func writeRegexp(b *bytes.Buffer, re *Regexp) {
|
||||
switch re.Op {
|
||||
default:
|
||||
b.WriteString("<invalid op" + strconv.Itoa(int(re.Op)) + ">")
|
||||
case OpNoMatch:
|
||||
b.WriteString(`[^\x00-\x{10FFFF}]`)
|
||||
case OpEmptyMatch:
|
||||
b.WriteString(`(?:)`)
|
||||
case OpLiteral:
|
||||
for _, r := range re.Rune {
|
||||
escape(b, r, false)
|
||||
}
|
||||
case OpCharClass:
|
||||
if len(re.Rune)%2 != 0 {
|
||||
b.WriteString(`[invalid char class]`)
|
||||
break
|
||||
}
|
||||
b.WriteRune('[')
|
||||
if len(re.Rune) > 0 && re.Rune[0] == 0 && re.Rune[len(re.Rune)-1] == unicode.MaxRune {
|
||||
// Contains 0 and MaxRune. Probably a negated class.
|
||||
// Print the gaps.
|
||||
b.WriteRune('^')
|
||||
for i := 1; i < len(re.Rune)-1; i += 2 {
|
||||
lo, hi := re.Rune[i]+1, re.Rune[i+1]-1
|
||||
escape(b, lo, lo == '-')
|
||||
if lo != hi {
|
||||
b.WriteRune('-')
|
||||
escape(b, hi, hi == '-')
|
||||
}
|
||||
}
|
||||
} else {
|
||||
for i := 0; i < len(re.Rune); i += 2 {
|
||||
lo, hi := re.Rune[i], re.Rune[i+1]
|
||||
escape(b, lo, lo == '-')
|
||||
if lo != hi {
|
||||
b.WriteRune('-')
|
||||
escape(b, hi, hi == '-')
|
||||
}
|
||||
}
|
||||
}
|
||||
b.WriteRune(']')
|
||||
case OpAnyCharNotNL:
|
||||
b.WriteString(`[^\n]`)
|
||||
case OpAnyChar:
|
||||
b.WriteRune('.')
|
||||
case OpBeginLine:
|
||||
b.WriteRune('^')
|
||||
case OpEndLine:
|
||||
b.WriteRune('$')
|
||||
case OpBeginText:
|
||||
b.WriteString(`\A`)
|
||||
case OpEndText:
|
||||
b.WriteString(`\z`)
|
||||
case OpWordBoundary:
|
||||
b.WriteString(`\b`)
|
||||
case OpNoWordBoundary:
|
||||
b.WriteString(`\B`)
|
||||
case OpCapture:
|
||||
if re.Name != "" {
|
||||
b.WriteString(`(?P<`)
|
||||
b.WriteString(re.Name)
|
||||
b.WriteRune('>')
|
||||
} else {
|
||||
b.WriteRune('(')
|
||||
}
|
||||
writeRegexp(b, re.Sub[0])
|
||||
b.WriteRune(')')
|
||||
case OpStar, OpPlus, OpQuest, OpRepeat:
|
||||
if sub := re.Sub[0]; sub.Op > OpCapture {
|
||||
b.WriteString(`(?:`)
|
||||
writeRegexp(b, sub)
|
||||
b.WriteString(`)`)
|
||||
} else {
|
||||
writeRegexp(b, sub)
|
||||
}
|
||||
switch re.Op {
|
||||
case OpStar:
|
||||
b.WriteRune('*')
|
||||
case OpPlus:
|
||||
b.WriteRune('+')
|
||||
case OpQuest:
|
||||
b.WriteRune('?')
|
||||
case OpRepeat:
|
||||
b.WriteRune('{')
|
||||
b.WriteString(strconv.Itoa(re.Min))
|
||||
if re.Max != re.Min {
|
||||
b.WriteRune(',')
|
||||
if re.Max >= 0 {
|
||||
b.WriteString(strconv.Itoa(re.Max))
|
||||
}
|
||||
}
|
||||
b.WriteRune('}')
|
||||
}
|
||||
case OpConcat:
|
||||
for _, sub := range re.Sub {
|
||||
if sub.Op == OpAlternate {
|
||||
b.WriteString(`(?:`)
|
||||
writeRegexp(b, sub)
|
||||
b.WriteString(`)`)
|
||||
} else {
|
||||
writeRegexp(b, sub)
|
||||
}
|
||||
}
|
||||
case OpAlternate:
|
||||
for i, sub := range re.Sub {
|
||||
if i > 0 {
|
||||
b.WriteRune('|')
|
||||
}
|
||||
writeRegexp(b, sub)
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
func (re *Regexp) String() string {
|
||||
var b bytes.Buffer
|
||||
writeRegexp(&b, re)
|
||||
return b.String()
|
||||
}
|
||||
|
||||
const meta = `\.+*?()|[]{}^$`
|
||||
|
||||
func escape(b *bytes.Buffer, r int, force bool) {
|
||||
if unicode.IsPrint(r) {
|
||||
if strings.IndexRune(meta, r) >= 0 || force {
|
||||
b.WriteRune('\\')
|
||||
}
|
||||
b.WriteRune(r)
|
||||
return
|
||||
}
|
||||
|
||||
switch r {
|
||||
case '\a':
|
||||
b.WriteString(`\a`)
|
||||
case '\f':
|
||||
b.WriteString(`\f`)
|
||||
case '\n':
|
||||
b.WriteString(`\n`)
|
||||
case '\r':
|
||||
b.WriteString(`\r`)
|
||||
case '\t':
|
||||
b.WriteString(`\t`)
|
||||
case '\v':
|
||||
b.WriteString(`\v`)
|
||||
default:
|
||||
b.WriteString(`\x{`)
|
||||
b.WriteString(strconv.Itob(r, 16))
|
||||
b.WriteString(`}`)
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user