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Commit a0feb325 authored by Rob Pike's avatar Rob Pike
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remove some incorrect capitalizations. 

add commentary.

R=rsc
DELTA=231  (41 added, 24 deleted, 166 changed)
OCL=25724
CL=25726
parent 811dd258
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Showing with 193 additions and 176 deletions
src/lib/regexp/all_test.go
View file @ a0feb325
......@@ -85,7 +85,7 @@ var matches = []tester {
tester{ `a*(|(b))c*`, "aacc", vec{0,4, 2,2, -1,-1} },
}
func compileTest(t *testing.T, expr string, error *os.Error) regexp.Regexp {
func compileTest(t *testing.T, expr string, error *os.Error) *regexp.Regexp {
re, err := regexp.Compile(expr);
if err != error {
t.Error("compiling `", expr, "`; unexpected error: ", err.String());
......
src/lib/regexp/regexp.go
View file @ a0feb325
......@@ -2,8 +2,25 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Regular expression library.
// Package regexp implements a simple regular expression library.
//
// The syntax of the regular expressions accepted is:
//
// regexp:
// concatenation { '|' concatenation }
// concatenation:
// { closure }
//
// closure:
// term [ '*' | '+' | '?' ]
// term:
// '^'
// '$'
// '.'
// character
// '[' [ '^' ] character-ranges ']'
// '(' regexp ')'
//
package regexp
import (
......@@ -14,7 +31,7 @@ import (
var debug = false;
// Error codes returned by faliures to parse an expression.
var ErrInternal = os.NewError("internal error");
var ErrUnmatchedLpar = os.NewError("unmatched '('");
var ErrUnmatchedRpar = os.NewError("unmatched ')'");
......@@ -28,28 +45,30 @@ var ErrBadBackslash = os.NewError("illegal backslash escape");
// An instruction executed by the NFA
type instr interface {
Type() int; // the type of this instruction: _CHAR, _ANY, etc.
Next() instr; // the instruction to execute after this one
SetNext(i instr);
Index() int;
SetIndex(i int);
Print();
kind() int; // the type of this instruction: _CHAR, _ANY, etc.
next() instr; // the instruction to execute after this one
setNext(i instr);
index() int;
setIndex(i int);
print();
}
// Fields and methods common to all instructions
type common struct {
next instr;
index int;
_next instr;
_index int;
}
func (c *common) Next() instr { return c.next }
func (c *common) SetNext(i instr) { c.next = i }
func (c *common) Index() int { return c.index }
func (c *common) SetIndex(i int) { c.index = i }
func (c *common) next() instr { return c._next }
func (c *common) setNext(i instr) { c._next = i }
func (c *common) index() int { return c._index }
func (c *common) setIndex(i int) { c._index = i }
type _RE struct {
// The representation of a compiled regular expression.
// The public interface is entirely through methods.
type Regexp struct {
expr string; // the original expression
ch chan<- *_RE; // reply channel when we're done
ch chan<- *Regexp; // reply channel when we're done
error *os.Error; // compile- or run-time error; nil if OK
inst *array.Array;
start instr;
......@@ -76,32 +95,32 @@ type _Start struct {
common
}
func (start *_Start) Type() int { return _START }
func (start *_Start) Print() { print("start") }
func (start *_Start) kind() int { return _START }
func (start *_Start) print() { print("start") }
// --- END end of program
type _End struct {
common
}
func (end *_End) Type() int { return _END }
func (end *_End) Print() { print("end") }
func (end *_End) kind() int { return _END }
func (end *_End) print() { print("end") }
// --- BOT beginning of text
type _Bot struct {
common
}
func (bot *_Bot) Type() int { return _BOT }
func (bot *_Bot) Print() { print("bot") }
func (bot *_Bot) kind() int { return _BOT }
func (bot *_Bot) print() { print("bot") }
// --- EOT end of text
type _Eot struct {
common
}
func (eot *_Eot) Type() int { return _EOT }
func (eot *_Eot) Print() { print("eot") }
func (eot *_Eot) kind() int { return _EOT }
func (eot *_Eot) print() { print("eot") }
// --- CHAR a regular character
type _Char struct {
......@@ -109,8 +128,8 @@ type _Char struct {
char int;
}
func (char *_Char) Type() int { return _CHAR }
func (char *_Char) Print() { print("char ", string(char.char)) }
func (char *_Char) kind() int { return _CHAR }
func (char *_Char) print() { print("char ", string(char.char)) }
func newChar(char int) *_Char {
c := new(_Char);
......@@ -128,9 +147,9 @@ type _CharClass struct {
ranges *array.IntArray;
}
func (cclass *_CharClass) Type() int { return _CHARCLASS }
func (cclass *_CharClass) kind() int { return _CHARCLASS }
func (cclass *_CharClass) Print() {
func (cclass *_CharClass) print() {
print("charclass");
if cclass.negate {
print(" (negated)");
......@@ -146,13 +165,13 @@ func (cclass *_CharClass) Print() {
}
}
func (cclass *_CharClass) AddRange(a, b int) {
func (cclass *_CharClass) addRange(a, b int) {
// range is a through b inclusive
cclass.ranges.Push(a);
cclass.ranges.Push(b);
}
func (cclass *_CharClass) Matches(c int) bool {
func (cclass *_CharClass) matches(c int) bool {
for i := 0; i < cclass.ranges.Len(); i = i+2 {
min := cclass.ranges.At(i);
max := cclass.ranges.At(i+1);
......@@ -174,8 +193,8 @@ type _Any struct {
common
}
func (any *_Any) Type() int { return _ANY }
func (any *_Any) Print() { print("any") }
func (any *_Any) kind() int { return _ANY }
func (any *_Any) print() { print("any") }
// --- BRA parenthesized expression
type _Bra struct {
......@@ -183,8 +202,8 @@ type _Bra struct {
n int; // subexpression number
}
func (bra *_Bra) Type() int { return _BRA }
func (bra *_Bra) Print() { print("bra", bra.n); }
func (bra *_Bra) kind() int { return _BRA }
func (bra *_Bra) print() { print("bra", bra.n); }
// --- EBRA end of parenthesized expression
type _Ebra struct {
......@@ -192,8 +211,8 @@ type _Ebra struct {
n int; // subexpression number
}
func (ebra *_Ebra) Type() int { return _EBRA }
func (ebra *_Ebra) Print() { print("ebra ", ebra.n); }
func (ebra *_Ebra) kind() int { return _EBRA }
func (ebra *_Ebra) print() { print("ebra ", ebra.n); }
// --- ALT alternation
type _Alt struct {
......@@ -201,32 +220,32 @@ type _Alt struct {
left instr; // other branch
}
func (alt *_Alt) Type() int { return _ALT }
func (alt *_Alt) Print() { print("alt(", alt.left.Index(), ")"); }
func (alt *_Alt) kind() int { return _ALT }
func (alt *_Alt) print() { print("alt(", alt.left.index(), ")"); }
// --- NOP no operation
type _Nop struct {
common
}
func (nop *_Nop) Type() int { return _NOP }
func (nop *_Nop) Print() { print("nop") }
func (nop *_Nop) kind() int { return _NOP }
func (nop *_Nop) print() { print("nop") }
// report error and exit compiling/executing goroutine
func (re *_RE) Error(err *os.Error) {
func (re *Regexp) setError(err *os.Error) {
re.error = err;
re.ch <- re;
sys.Goexit();
}
func (re *_RE) Add(i instr) instr {
i.SetIndex(re.inst.Len());
func (re *Regexp) add(i instr) instr {
i.setIndex(re.inst.Len());
re.inst.Push(i);
return i;
}
type parser struct {
re *_RE;
re *Regexp;
nlpar int; // number of unclosed lpars
pos int;
ch int;
......@@ -249,33 +268,14 @@ func (p *parser) nextc() int {
return p.ch;
}
func newParser(re *_RE) *parser {
func newParser(re *Regexp) *parser {
p := new(parser);
p.re = re;
p.nextc(); // load p.ch
return p;
}
/*
Grammar:
regexp:
concatenation { '|' concatenation }
concatenation:
{ closure }
closure:
term [ '*' | '+' | '?' ]
term:
'^'
'$'
'.'
character
'[' [ '^' ] character-ranges ']'
'(' regexp ')'
*/
func (p *parser) Regexp() (start, end instr)
func (p *parser) regexp() (start, end instr)
var iNULL instr
......@@ -299,9 +299,9 @@ func specialcclass(c int) bool {
return false
}
func (p *parser) CharClass() instr {
func (p *parser) charClass() instr {
cc := newCharClass();
p.re.Add(cc);
p.re.add(cc);
if p.c() == '^' {
cc.negate = true;
p.nextc();
......@@ -311,22 +311,22 @@ func (p *parser) CharClass() instr {
switch c := p.c(); c {
case ']', endOfFile:
if left >= 0 {
p.re.Error(ErrBadRange);
p.re.setError(ErrBadRange);
}
return cc;
case '-': // do this before backslash processing
p.re.Error(ErrBadRange);
p.re.setError(ErrBadRange);
case '\\':
c = p.nextc();
switch {
case c == endOfFile:
p.re.Error(ErrExtraneousBackslash);
p.re.setError(ErrExtraneousBackslash);
case c == 'n':
c = '\n';
case specialcclass(c):
// c is as delivered
default:
p.re.Error(ErrBadBackslash);
p.re.setError(ErrBadBackslash);
}
fallthrough;
default:
......@@ -337,49 +337,49 @@ func (p *parser) CharClass() instr {
p.nextc();
left = c;
} else { // single char
cc.AddRange(c, c);
cc.addRange(c, c);
}
case left <= c: // second of pair
cc.AddRange(left, c);
cc.addRange(left, c);
left = -1;
default:
p.re.Error(ErrBadRange);
p.re.setError(ErrBadRange);
}
}
}
return iNULL
}
func (p *parser) Term() (start, end instr) {
func (p *parser) term() (start, end instr) {
switch c := p.c(); c {
case '|', endOfFile:
return iNULL, iNULL;
case '*', '+':
p.re.Error(ErrBareClosure);
p.re.setError(ErrBareClosure);
case ')':
if p.nlpar == 0 {
p.re.Error(ErrUnmatchedRpar);
p.re.setError(ErrUnmatchedRpar);
}
return iNULL, iNULL;
case ']':
p.re.Error(ErrUnmatchedRbkt);
p.re.setError(ErrUnmatchedRbkt);
case '^':
p.nextc();
start = p.re.Add(new(_Bot));
start = p.re.add(new(_Bot));
return start, start;
case '$':
p.nextc();
start = p.re.Add(new(_Eot));
start = p.re.add(new(_Eot));
return start, start;
case '.':
p.nextc();
start = p.re.Add(new(_Any));
start = p.re.add(new(_Any));
return start, start;
case '[':
p.nextc();
start = p.CharClass();
start = p.charClass();
if p.c() != ']' {
p.re.Error(ErrUnmatchedLbkt);
p.re.setError(ErrUnmatchedLbkt);
}
p.nextc();
return start, start;
......@@ -388,50 +388,52 @@ func (p *parser) Term() (start, end instr) {
p.nlpar++;
p.re.nbra++; // increment first so first subexpr is \1
nbra := p.re.nbra;
start, end = p.Regexp();
start, end = p.regexp();
if p.c() != ')' {
p.re.Error(ErrUnmatchedLpar);
p.re.setError(ErrUnmatchedLpar);
}
p.nlpar--;
p.nextc();
bra := new(_Bra);
p.re.Add(bra);
p.re.add(bra);
ebra := new(_Ebra);
p.re.Add(ebra);
p.re.add(ebra);
bra.n = nbra;
ebra.n = nbra;
if start == iNULL {
if end == iNULL { p.re.Error(ErrInternal) }
if end == iNULL {
p.re.setError(ErrInternal)
}
start = ebra
} else {
end.SetNext(ebra);
end.setNext(ebra);
}
bra.SetNext(start);
bra.setNext(start);
return bra, ebra;
case '\\':
c = p.nextc();
switch {
case c == endOfFile:
p.re.Error(ErrExtraneousBackslash);
p.re.setError(ErrExtraneousBackslash);
case c == 'n':
c = '\n';
case special(c):
// c is as delivered
default:
p.re.Error(ErrBadBackslash);
p.re.setError(ErrBadBackslash);
}
fallthrough;
default:
p.nextc();
start = newChar(c);
p.re.Add(start);
p.re.add(start);
return start, start
}
panic("unreachable");
}
func (p *parser) Closure() (start, end instr) {
start, end = p.Term();
func (p *parser) closure() (start, end instr) {
start, end = p.term();
if start == iNULL {
return
}
......@@ -439,27 +441,27 @@ func (p *parser) Closure() (start, end instr) {
case '*':
// (start,end)*:
alt := new(_Alt);
p.re.Add(alt);
end.SetNext(alt); // after end, do alt
p.re.add(alt);
end.setNext(alt); // after end, do alt
alt.left = start; // alternate brach: return to start
start = alt; // alt becomes new (start, end)
end = alt;
case '+':
// (start,end)+:
alt := new(_Alt);
p.re.Add(alt);
end.SetNext(alt); // after end, do alt
p.re.add(alt);
end.setNext(alt); // after end, do alt
alt.left = start; // alternate brach: return to start
end = alt; // start is unchanged; end is alt
case '?':
// (start,end)?:
alt := new(_Alt);
p.re.Add(alt);
p.re.add(alt);
nop := new(_Nop);
p.re.Add(nop);
p.re.add(nop);
alt.left = start; // alternate branch is start
alt.next = nop; // follow on to nop
end.SetNext(nop); // after end, go to nop
alt.setNext(nop); // follow on to nop
end.setNext(nop); // after end, go to nop
start = alt; // start is now alt
end = nop; // end is nop pointed to by both branches
default:
......@@ -467,49 +469,49 @@ func (p *parser) Closure() (start, end instr) {
}
switch p.nextc() {
case '*', '+', '?':
p.re.Error(ErrBadClosure);
p.re.setError(ErrBadClosure);
}
return
}
func (p *parser) Concatenation() (start, end instr) {
func (p *parser) concatenation() (start, end instr) {
start, end = iNULL, iNULL;
for {
nstart, nend := p.Closure();
nstart, nend := p.closure();
switch {
case nstart == iNULL: // end of this concatenation
if start == iNULL { // this is the empty string
nop := p.re.Add(new(_Nop));
nop := p.re.add(new(_Nop));
return nop, nop;
}
return;
case start == iNULL: // this is first element of concatenation
start, end = nstart, nend;
default:
end.SetNext(nstart);
end.setNext(nstart);
end = nend;
}
}
panic("unreachable");
}
func (p *parser) Regexp() (start, end instr) {
start, end = p.Concatenation();
func (p *parser) regexp() (start, end instr) {
start, end = p.concatenation();
for {
switch p.c() {
default:
return;
case '|':
p.nextc();
nstart, nend := p.Concatenation();
nstart, nend := p.concatenation();
alt := new(_Alt);
p.re.Add(alt);
p.re.add(alt);
alt.left = start;
alt.next = nstart;
alt.setNext(nstart);
nop := new(_Nop);
p.re.Add(nop);
end.SetNext(nop);
nend.SetNext(nop);
p.re.add(nop);
end.setNext(nop);
nend.setNext(nop);
start, end = alt, nop;
}
}
......@@ -517,80 +519,75 @@ func (p *parser) Regexp() (start, end instr) {
}
func unNop(i instr) instr {
for i.Type() == _NOP {
i = i.Next()
for i.kind() == _NOP {
i = i.next()
}
return i
}
func (re *_RE) EliminateNops() {
func (re *Regexp) eliminateNops() {
for i := 0; i < re.inst.Len(); i++ {
inst := re.inst.At(i).(instr);
if inst.Type() == _END {
if inst.kind() == _END {
continue
}
inst.SetNext(unNop(inst.Next()));
if inst.Type() == _ALT {
inst.setNext(unNop(inst.next()));
if inst.kind() == _ALT {
alt := inst.(*_Alt);
alt.left = unNop(alt.left);
}
}
}
func (re *_RE) Dump() {
func (re *Regexp) dump() {
for i := 0; i < re.inst.Len(); i++ {
inst := re.inst.At(i).(instr);
print(inst.Index(), ": ");
inst.Print();
if inst.Type() != _END {
print(" -> ", inst.Next().Index())
print(inst.index(), ": ");
inst.print();
if inst.kind() != _END {
print(" -> ", inst.next().index())
}
print("\n");
}
}
func (re *_RE) DoParse() {
func (re *Regexp) doParse() {
p := newParser(re);
start := new(_Start);
re.Add(start);
s, e := p.Regexp();
start.next = s;
re.add(start);
s, e := p.regexp();
start.setNext(s);
re.start = start;
e.SetNext(re.Add(new(_End)));
e.setNext(re.add(new(_End)));
if debug {
re.Dump();
re.dump();
println();
}
re.EliminateNops();
re.eliminateNops();
if debug {
re.Dump();
re.dump();
println();
}
}
func compiler(str string, ch chan *_RE) {
re := new(_RE);
func compiler(str string, ch chan *Regexp) {
re := new(Regexp);
re.expr = str;
re.inst = array.New(0);
re.ch = ch;
re.DoParse();
re.doParse();
ch <- re;
}
// Public interface has only execute functionality
type Regexp interface {
Execute(s string) []int;
Match(s string) bool;
MatchStrings(s string) []string;
}
// Compile in separate goroutine; wait for result
func Compile(str string) (regexp Regexp, error *os.Error) {
ch := make(chan *_RE);
// Compile parses a regular expression and returns, if successful, a Regexp
// object that can be used to match against text.
func Compile(str string) (regexp *Regexp, error *os.Error) {
// Compile in a separate goroutine and wait for the result.
ch := make(chan *Regexp);
go compiler(str, ch);
re := <-ch;
return re, re.error
......@@ -604,13 +601,13 @@ type state struct {
// Append new state to to-do list. Leftmost-longest wins so avoid
// adding a state that's already active.
func addState(s []state, inst instr, match []int) []state {
index := inst.Index();
index := inst.index();
l := len(s);
pos := match[0];
// TODO: Once the state is a vector and we can do insert, have inputs always
// go in order correctly and this "earlier" test is never necessary,
for i := 0; i < l; i++ {
if s[i].inst.Index() == index && // same instruction
if s[i].inst.index() == index && // same instruction
s[i].match[0] < pos { // earlier match already going; lefmost wins
return s
}
......@@ -628,7 +625,7 @@ func addState(s []state, inst instr, match []int) []state {
return s;
}
func (re *_RE) DoExecute(str string, pos int) []int {
func (re *Regexp) doExecute(str string, pos int) []int {
var s [2][]state; // TODO: use a vector when state values (not ptrs) can be vector elements
s[0] = make([]state, 10)[0:0];
s[1] = make([]state, 10)[0:0];
......@@ -643,7 +640,7 @@ func (re *_RE) DoExecute(str string, pos int) []int {
match[i] = -1; // no match seen; catches cases like "a(b)?c" on "ac"
}
match[0] = pos;
s[out] = addState(s[out], re.start.Next(), match);
s[out] = addState(s[out], re.start.next(), match);
}
in, out = out, in; // old out state is new in state
s[out] = s[out][0:0]; // clear out state
......@@ -658,35 +655,35 @@ func (re *_RE) DoExecute(str string, pos int) []int {
}
for i := 0; i < len(s[in]); i++ {
st := s[in][i];
switch s[in][i].inst.Type() {
switch s[in][i].inst.kind() {
case _BOT:
if pos == 0 {
s[in] = addState(s[in], st.inst.Next(), st.match)
s[in] = addState(s[in], st.inst.next(), st.match)
}
case _EOT:
if pos == len(str) {
s[in] = addState(s[in], st.inst.Next(), st.match)
s[in] = addState(s[in], st.inst.next(), st.match)
}
case _CHAR:
if c == st.inst.(*_Char).char {
s[out] = addState(s[out], st.inst.Next(), st.match)
s[out] = addState(s[out], st.inst.next(), st.match)
}
case _CHARCLASS:
if st.inst.(*_CharClass).Matches(c) {
s[out] = addState(s[out], st.inst.Next(), st.match)
if st.inst.(*_CharClass).matches(c) {
s[out] = addState(s[out], st.inst.next(), st.match)
}
case _ANY:
if c != endOfFile {
s[out] = addState(s[out], st.inst.Next(), st.match)
s[out] = addState(s[out], st.inst.next(), st.match)
}
case _BRA:
n := st.inst.(*_Bra).n;
st.match[2*n] = pos;
s[in] = addState(s[in], st.inst.Next(), st.match);
s[in] = addState(s[in], st.inst.next(), st.match);
case _EBRA:
n := st.inst.(*_Ebra).n;
st.match[2*n+1] = pos;
s[in] = addState(s[in], st.inst.Next(), st.match);
s[in] = addState(s[in], st.inst.next(), st.match);
case _ALT:
s[in] = addState(s[in], st.inst.(*_Alt).left, st.match);
// give other branch a copy of this match vector
......@@ -694,7 +691,7 @@ func (re *_RE) DoExecute(str string, pos int) []int {
for i := 0; i < len(s1); i++ {
s1[i] = st.match[i]
}
s[in] = addState(s[in], st.inst.Next(), s1);
s[in] = addState(s[in], st.inst.next(), s1);
case _END:
// choose leftmost longest
if !found || // first
......@@ -705,7 +702,7 @@ func (re *_RE) DoExecute(str string, pos int) []int {
}
found = true;
default:
st.inst.Print();
st.inst.print();
panic("unknown instruction in execute");
}
}
......@@ -715,30 +712,50 @@ func (re *_RE) DoExecute(str string, pos int) []int {
}
func (re *_RE) Execute(s string) []int {
return re.DoExecute(s, 0)
// Execute matches the Regexp against the string s.
// The return value is an array of integers, in pairs, identifying the positions of
// substrings matched by the expression.
// s[a[0]:a[1]] is the substring matched by the entire expression.
// s[a[2*i]:a[2*i+1]] for i > 0 is the substring matched by the ith parenthesized subexpression.
// A value of -1 means the subexpression did not match any element of the string.
// An empty array means "no match".
// (Regexp is an internal type that implements the Regexp interface.)
func (re *Regexp) Execute(s string) (a []int) {
return re.doExecute(s, 0)
}
func (re *_RE) Match(s string) bool {
return len(re.DoExecute(s, 0)) > 0
// Match returns whether the Regexp matches the string s.
// The return value is a boolean: true for match, false for no match.
// (Regexp is an internal type that implements the Regexp interface.)
func (re *Regexp) Match(s string) bool {
return len(re.doExecute(s, 0)) > 0
}
func (re *_RE) MatchStrings(s string) []string {
r := re.DoExecute(s, 0);
// MatchStrings matches the Regexp against the string s.
// The return value is an array of strings matched by the expression.
// a[0] is the substring matched by the entire expression.
// a[i] for i > 0 is the substring matched by the ith parenthesized subexpression.
// An empty array means ``no match''.
// (Regexp is an internal type that implements the Regexp interface.)
func (re *Regexp) MatchStrings(s string) (a []string) {
r := re.doExecute(s, 0);
if r == nil {
return nil
}
a := make([]string, len(r)/2);
a = make([]string, len(r)/2);
for i := 0; i < len(r); i += 2 {
a[i/2] = s[r[i] : r[i+1]]
if r[i] != -1 { // -1 means no match for this subexpression
a[i/2] = s[r[i] : r[i+1]]
}
}
return a
return
}
// Exported function for simple boolean check. Anything more fancy
// needs a call to Compile.
// Match checks whether a textual regular expression
// matches a substring. More complicated queries need
// to use Compile and the full Regexp interface.
func Match(pattern string, s string) (matched bool, error *os.Error) {
re, err := Compile(pattern);
if err != nil {
......
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