/usr/lib/gcc/x86_64-linux-gnu/5/include/d/std/regex/internal/ir.d is in libphobos-5-dev 5.5.0-12ubuntu1.
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Implementation of std.regex IR, an intermediate representation
of a regular expression pattern.
This is a common ground between frontend regex component (parser)
and backend components - generators, matchers and other "filters".
*/
module std.regex.internal.ir;
package(std.regex):
import std.exception, std.uni, std.typetuple, std.traits, std.range;
// just a common trait, may be moved elsewhere
alias BasicElementOf(Range) = Unqual!(ElementEncodingType!Range);
// heuristic value determines maximum CodepointSet length suitable for linear search
enum maxCharsetUsed = 6;
// another variable to tweak behavior of caching generated Tries for character classes
enum maxCachedTries = 8;
alias Trie = CodepointSetTrie!(13, 8);
alias makeTrie = codepointSetTrie!(13, 8);
Trie[CodepointSet] trieCache;
//accessor with caching
@trusted Trie getTrie(CodepointSet set)
{// @@@BUG@@@ 6357 almost all properties of AA are not @safe
if(__ctfe || maxCachedTries == 0)
return makeTrie(set);
else
{
auto p = set in trieCache;
if(p)
return *p;
if(trieCache.length == maxCachedTries)
{
// flush entries in trieCache
trieCache = null;
}
return (trieCache[set] = makeTrie(set));
}
}
@trusted auto memoizeExpr(string expr)()
{
if(__ctfe)
return mixin(expr);
alias T = typeof(mixin(expr));
static T slot;
static bool initialized;
if(!initialized)
{
slot = mixin(expr);
initialized = true;
}
return slot;
}
//property for \w character class
@property CodepointSet wordCharacter()
{
return memoizeExpr!("unicode.Alphabetic | unicode.Mn | unicode.Mc
| unicode.Me | unicode.Nd | unicode.Pc")();
}
@property Trie wordTrie()
{
return memoizeExpr!("makeTrie(wordCharacter)")();
}
// some special Unicode white space characters
private enum NEL = '\u0085', LS = '\u2028', PS = '\u2029';
//Regular expression engine/parser options:
// global - search all nonoverlapping matches in input
// casefold - case insensitive matching, do casefolding on match in unicode mode
// freeform - ignore whitespace in pattern, to match space use [ ] or \s
// multiline - switch ^, $ detect start and end of linesinstead of just start and end of input
enum RegexOption: uint {
global = 0x1,
casefold = 0x2,
freeform = 0x4,
nonunicode = 0x8,
multiline = 0x10,
singleline = 0x20
}
//do not reorder this list
alias RegexOptionNames = TypeTuple!('g', 'i', 'x', 'U', 'm', 's');
static assert( RegexOption.max < 0x80);
// flags that allow guide execution of engine
enum RegexInfo : uint { oneShot = 0x80 }
// IR bit pattern: 0b1_xxxxx_yy
// where yy indicates class of instruction, xxxxx for actual operation code
// 00: atom, a normal instruction
// 01: open, opening of a group, has length of contained IR in the low bits
// 10: close, closing of a group, has length of contained IR in the low bits
// 11 unused
//
// Loops with Q (non-greedy, with ? mark) must have the same size / other properties as non Q version
// Possible changes:
//* merge group, option, infinite/repeat start (to never copy during parsing of (a|b){1,2})
//* reorganize groups to make n args easier to find, or simplify the check for groups of similar ops
// (like lookaround), or make it easier to identify hotspots.
enum IR:uint {
Char = 0b1_00000_00, //a character
Any = 0b1_00001_00, //any character
CodepointSet = 0b1_00010_00, //a most generic CodepointSet [...]
Trie = 0b1_00011_00, //CodepointSet implemented as Trie
//match with any of a consecutive OrChar's in this sequence
//(used for case insensitive match)
//OrChar holds in upper two bits of data total number of OrChars in this _sequence_
//the drawback of this representation is that it is difficult
// to detect a jump in the middle of it
OrChar = 0b1_00100_00,
Nop = 0b1_00101_00, //no operation (padding)
End = 0b1_00110_00, //end of program
Bol = 0b1_00111_00, //beginning of a string ^
Eol = 0b1_01000_00, //end of a string $
Wordboundary = 0b1_01001_00, //boundary of a word
Notwordboundary = 0b1_01010_00, //not a word boundary
Backref = 0b1_01011_00, //backreference to a group (that has to be pinned, i.e. locally unique) (group index)
GroupStart = 0b1_01100_00, //start of a group (x) (groupIndex+groupPinning(1bit))
GroupEnd = 0b1_01101_00, //end of a group (x) (groupIndex+groupPinning(1bit))
Option = 0b1_01110_00, //start of an option within an alternation x | y (length)
GotoEndOr = 0b1_01111_00, //end of an option (length of the rest)
//... any additional atoms here
OrStart = 0b1_00000_01, //start of alternation group (length)
OrEnd = 0b1_00000_10, //end of the or group (length,mergeIndex)
//with this instruction order
//bit mask 0b1_00001_00 could be used to test/set greediness
InfiniteStart = 0b1_00001_01, //start of an infinite repetition x* (length)
InfiniteEnd = 0b1_00001_10, //end of infinite repetition x* (length,mergeIndex)
InfiniteQStart = 0b1_00010_01, //start of a non eager infinite repetition x*? (length)
InfiniteQEnd = 0b1_00010_10, //end of non eager infinite repetition x*? (length,mergeIndex)
RepeatStart = 0b1_00011_01, //start of a {n,m} repetition (length)
RepeatEnd = 0b1_00011_10, //end of x{n,m} repetition (length,step,minRep,maxRep)
RepeatQStart = 0b1_00100_01, //start of a non eager x{n,m}? repetition (length)
RepeatQEnd = 0b1_00100_10, //end of non eager x{n,m}? repetition (length,step,minRep,maxRep)
//
LookaheadStart = 0b1_00101_01, //begin of the lookahead group (length)
LookaheadEnd = 0b1_00101_10, //end of a lookahead group (length)
NeglookaheadStart = 0b1_00110_01, //start of a negative lookahead (length)
NeglookaheadEnd = 0b1_00110_10, //end of a negative lookahead (length)
LookbehindStart = 0b1_00111_01, //start of a lookbehind (length)
LookbehindEnd = 0b1_00111_10, //end of a lookbehind (length)
NeglookbehindStart= 0b1_01000_01, //start of a negative lookbehind (length)
NeglookbehindEnd = 0b1_01000_10, //end of negative lookbehind (length)
}
//a shorthand for IR length - full length of specific opcode evaluated at compile time
template IRL(IR code)
{
enum uint IRL = lengthOfIR(code);
}
static assert (IRL!(IR.LookaheadStart) == 3);
//how many parameters follow the IR, should be optimized fixing some IR bits
int immediateParamsIR(IR i){
switch (i){
case IR.OrEnd,IR.InfiniteEnd,IR.InfiniteQEnd:
return 1;
case IR.RepeatEnd, IR.RepeatQEnd:
return 4;
case IR.LookaheadStart, IR.NeglookaheadStart, IR.LookbehindStart, IR.NeglookbehindStart:
return 2;
default:
return 0;
}
}
//full length of IR instruction inlcuding all parameters that might follow it
int lengthOfIR(IR i)
{
return 1 + immediateParamsIR(i);
}
//full length of the paired IR instruction inlcuding all parameters that might follow it
int lengthOfPairedIR(IR i)
{
return 1 + immediateParamsIR(pairedIR(i));
}
//if the operation has a merge point (this relies on the order of the ops)
bool hasMerge(IR i)
{
return (i&0b11)==0b10 && i <= IR.RepeatQEnd;
}
//is an IR that opens a "group"
bool isStartIR(IR i)
{
return (i&0b11)==0b01;
}
//is an IR that ends a "group"
bool isEndIR(IR i)
{
return (i&0b11)==0b10;
}
//is a standalone IR
bool isAtomIR(IR i)
{
return (i&0b11)==0b00;
}
//makes respective pair out of IR i, swapping start/end bits of instruction
IR pairedIR(IR i)
{
assert(isStartIR(i) || isEndIR(i));
return cast(IR)(i ^ 0b11);
}
//encoded IR instruction
struct Bytecode
{
uint raw;
//natural constraints
enum maxSequence = 2+4;
enum maxData = 1<<22;
enum maxRaw = 1<<31;
this(IR code, uint data)
{
assert(data < (1<<22) && code < 256);
raw = code<<24 | data;
}
this(IR code, uint data, uint seq)
{
assert(data < (1<<22) && code < 256 );
assert(seq >= 2 && seq < maxSequence);
raw = code << 24 | (seq - 2)<<22 | data;
}
//store raw data
static Bytecode fromRaw(uint data)
{
Bytecode t;
t.raw = data;
return t;
}
//bit twiddling helpers
//0-arg template due to @@@BUG@@@ 10985
@property uint data()() const { return raw & 0x003f_ffff; }
//ditto
//0-arg template due to @@@BUG@@@ 10985
@property uint sequence()() const { return 2 + (raw >> 22 & 0x3); }
//ditto
//0-arg template due to @@@BUG@@@ 10985
@property IR code()() const { return cast(IR)(raw>>24); }
//ditto
@property bool hotspot() const { return hasMerge(code); }
//test the class of this instruction
@property bool isAtom() const { return isAtomIR(code); }
//ditto
@property bool isStart() const { return isStartIR(code); }
//ditto
@property bool isEnd() const { return isEndIR(code); }
//number of arguments for this instruction
@property int args() const { return immediateParamsIR(code); }
//mark this GroupStart or GroupEnd as referenced in backreference
void setBackrefence()
{
assert(code == IR.GroupStart || code == IR.GroupEnd);
raw = raw | 1 << 23;
}
//is referenced
@property bool backreference() const
{
assert(code == IR.GroupStart || code == IR.GroupEnd);
return cast(bool)(raw & 1 << 23);
}
//mark as local reference (for backrefs in lookarounds)
void setLocalRef()
{
assert(code == IR.Backref);
raw = raw | 1 << 23;
}
//is a local ref
@property bool localRef() const
{
assert(code == IR.Backref);
return cast(bool)(raw & 1 << 23);
}
//human readable name of instruction
@trusted @property string mnemonic()() const
{//@@@BUG@@@ to is @system
import std.conv;
return to!string(code);
}
//full length of instruction
@property uint length() const
{
return lengthOfIR(code);
}
//full length of respective start/end of this instruction
@property uint pairedLength() const
{
return lengthOfPairedIR(code);
}
//returns bytecode of paired instruction (assuming this one is start or end)
@property Bytecode paired() const
{//depends on bit and struct layout order
assert(isStart || isEnd);
return Bytecode.fromRaw(raw ^ 0b11 << 24);
}
//gets an index into IR block of the respective pair
uint indexOfPair(uint pc) const
{
assert(isStart || isEnd);
return isStart ? pc + data + length : pc - data - lengthOfPairedIR(code);
}
}
static assert(Bytecode.sizeof == 4);
//index entry structure for name --> number of submatch
struct NamedGroup
{
string name;
uint group;
}
//holds pair of start-end markers for a submatch
struct Group(DataIndex)
{
DataIndex begin, end;
@trusted string toString()() const
{
import std.format;
auto a = appender!string();
formattedWrite(a, "%s..%s", begin, end);
return a.data;
}
}
//debugging tool, prints out instruction along with opcodes
@trusted string disassemble(in Bytecode[] irb, uint pc, in NamedGroup[] dict=[])
{
import std.array, std.format;
auto output = appender!string();
formattedWrite(output,"%s", irb[pc].mnemonic);
switch(irb[pc].code)
{
case IR.Char:
formattedWrite(output, " %s (0x%x)",cast(dchar)irb[pc].data, irb[pc].data);
break;
case IR.OrChar:
formattedWrite(output, " %s (0x%x) seq=%d", cast(dchar)irb[pc].data, irb[pc].data, irb[pc].sequence);
break;
case IR.RepeatStart, IR.InfiniteStart, IR.Option, IR.GotoEndOr, IR.OrStart:
//forward-jump instructions
uint len = irb[pc].data;
formattedWrite(output, " pc=>%u", pc+len+IRL!(IR.RepeatStart));
break;
case IR.RepeatEnd, IR.RepeatQEnd: //backward-jump instructions
uint len = irb[pc].data;
formattedWrite(output, " pc=>%u min=%u max=%u step=%u",
pc - len, irb[pc + 3].raw, irb[pc + 4].raw, irb[pc + 2].raw);
break;
case IR.InfiniteEnd, IR.InfiniteQEnd, IR.OrEnd: //ditto
uint len = irb[pc].data;
formattedWrite(output, " pc=>%u", pc-len);
break;
case IR.LookaheadEnd, IR.NeglookaheadEnd: //ditto
uint len = irb[pc].data;
formattedWrite(output, " pc=>%u", pc-len);
break;
case IR.GroupStart, IR.GroupEnd:
uint n = irb[pc].data;
string name;
foreach(v;dict)
if(v.group == n)
{
name = "'"~v.name~"'";
break;
}
formattedWrite(output, " %s #%u " ~ (irb[pc].backreference ? "referenced" : ""),
name, n);
break;
case IR.LookaheadStart, IR.NeglookaheadStart, IR.LookbehindStart, IR.NeglookbehindStart:
uint len = irb[pc].data;
uint start = irb[pc+1].raw, end = irb[pc+2].raw;
formattedWrite(output, " pc=>%u [%u..%u]", pc + len + IRL!(IR.LookaheadStart), start, end);
break;
case IR.Backref: case IR.CodepointSet: case IR.Trie:
uint n = irb[pc].data;
formattedWrite(output, " %u", n);
if(irb[pc].code == IR.Backref)
formattedWrite(output, " %s", irb[pc].localRef ? "local" : "global");
break;
default://all data-free instructions
}
if(irb[pc].hotspot)
formattedWrite(output, " Hotspot %u", irb[pc+1].raw);
return output.data;
}
//disassemble the whole chunk
@trusted void printBytecode()(in Bytecode[] slice, in NamedGroup[] dict=[])
{
import std.stdio;
for(uint pc=0; pc<slice.length; pc += slice[pc].length)
writeln("\t", disassemble(slice, pc, dict));
}
/++
$(D Regex) object holds regular expression pattern in compiled form.
Instances of this object are constructed via calls to $(D regex).
This is an intended form for caching and storage of frequently
used regular expressions.
+/
struct Regex(Char)
{
//temporary workaround for identifier lookup
CodepointSet[] charsets; //
Bytecode[] ir; //compiled bytecode of pattern
@safe @property bool empty() const nothrow { return ir is null; }
@safe @property auto namedCaptures()
{
static struct NamedGroupRange
{
private:
NamedGroup[] groups;
size_t start;
size_t end;
public:
this(NamedGroup[] g, size_t s, size_t e)
{
assert(s <= e);
assert(e <= g.length);
groups = g;
start = s;
end = e;
}
@property string front() { return groups[start].name; }
@property string back() { return groups[end-1].name; }
@property bool empty() { return start >= end; }
@property size_t length() { return end - start; }
alias opDollar = length;
@property NamedGroupRange save()
{
return NamedGroupRange(groups, start, end);
}
void popFront() { assert(!empty); start++; }
void popBack() { assert(!empty); end--; }
string opIndex()(size_t i)
{
assert(start + i < end,
"Requested named group is out of range.");
return groups[start+i].name;
}
NamedGroupRange opSlice(size_t low, size_t high) {
assert(low <= high);
assert(start + high <= end);
return NamedGroupRange(groups, start + low, start + high);
}
NamedGroupRange opSlice() { return this.save; }
}
return NamedGroupRange(dict, 0, dict.length);
}
package(std.regex):
import std.regex.internal.kickstart; //TODO: get rid of this dependency
NamedGroup[] dict; //maps name -> user group number
uint ngroup; //number of internal groups
uint maxCounterDepth; //max depth of nested {n,m} repetitions
uint hotspotTableSize; //number of entries in merge table
uint threadCount;
uint flags; //global regex flags
public const(Trie)[] tries; //
uint[] backrefed; //bit array of backreferenced submatches
Kickstart!Char kickstart;
//bit access helper
uint isBackref(uint n)
{
if(n/32 >= backrefed.length)
return 0;
return backrefed[n / 32] & (1 << (n & 31));
}
//check if searching is not needed
void checkIfOneShot()
{
if(flags & RegexOption.multiline)
return;
L_CheckLoop:
for(uint i = 0; i < ir.length; i += ir[i].length)
{
switch(ir[i].code)
{
case IR.Bol:
flags |= RegexInfo.oneShot;
break L_CheckLoop;
case IR.GroupStart, IR.GroupEnd, IR.Eol, IR.Wordboundary, IR.Notwordboundary:
break;
default:
break L_CheckLoop;
}
}
}
//print out disassembly a program's IR
@trusted debug(std_regex_parser) void print() const
{//@@@BUG@@@ write is system
for(uint i = 0; i < ir.length; i += ir[i].length)
{
writefln("%d\t%s ", i, disassemble(ir, i, dict));
}
writeln("Total merge table size: ", hotspotTableSize);
writeln("Max counter nesting depth: ", maxCounterDepth);
}
}
//@@@BUG@@@ (unreduced) - public makes it inaccessible in std.regex.package (!)
/*public*/ struct StaticRegex(Char)
{
package(std.regex):
import std.regex.internal.backtracking;
alias Matcher = BacktrackingMatcher!(true);
alias MatchFn = bool function(ref Matcher!Char) @trusted;
MatchFn nativeFn;
public:
Regex!Char _regex;
alias _regex this;
this(Regex!Char re, MatchFn fn)
{
_regex = re;
nativeFn = fn;
}
}
// The stuff below this point is temporarrily part of IR module
// but may need better place in the future (all internals)
package(std.regex):
//Simple UTF-string abstraction compatible with stream interface
struct Input(Char)
if(is(Char :dchar))
{
import std.utf;
alias DataIndex = size_t;
enum { isLoopback = false };
alias String = const(Char)[];
String _origin;
size_t _index;
//constructs Input object out of plain string
this(String input, size_t idx = 0)
{
_origin = input;
_index = idx;
}
//codepoint at current stream position
bool nextChar(ref dchar res, ref size_t pos)
{
pos = _index;
if(_index == _origin.length)
return false;
res = std.utf.decode(_origin, _index);
return true;
}
@property bool atEnd(){
return _index == _origin.length;
}
bool search(Kickstart)(ref Kickstart kick, ref dchar res, ref size_t pos)
{
size_t idx = kick.search(_origin, _index);
_index = idx;
return nextChar(res, pos);
}
//index of at End position
@property size_t lastIndex(){ return _origin.length; }
//support for backtracker engine, might not be present
void reset(size_t index){ _index = index; }
String opSlice(size_t start, size_t end){ return _origin[start..end]; }
struct BackLooper
{
alias DataIndex = size_t;
enum { isLoopback = true };
String _origin;
size_t _index;
this(Input input, size_t index)
{
_origin = input._origin;
_index = index;
}
@trusted bool nextChar(ref dchar res,ref size_t pos)
{
pos = _index;
if(_index == 0)
return false;
res = _origin[0.._index].back;
_index -= std.utf.strideBack(_origin, _index);
return true;
}
@property atEnd(){ return _index == 0 || _index == std.utf.strideBack(_origin, _index); }
auto loopBack(size_t index){ return Input(_origin, index); }
//support for backtracker engine, might not be present
//void reset(size_t index){ _index = index ? index-std.utf.strideBack(_origin, index) : 0; }
void reset(size_t index){ _index = index; }
String opSlice(size_t start, size_t end){ return _origin[end..start]; }
//index of at End position
@property size_t lastIndex(){ return 0; }
}
auto loopBack(size_t index){ return BackLooper(this, index); }
}
//both helpers below are internal, on its own are quite "explosive"
//unsafe, no initialization of elements
@system T[] mallocArray(T)(size_t len)
{
import core.stdc.stdlib;
return (cast(T*)malloc(len * T.sizeof))[0 .. len];
}
//very unsafe, no initialization
@system T[] arrayInChunk(T)(size_t len, ref void[] chunk)
{
auto ret = (cast(T*)chunk.ptr)[0..len];
chunk = chunk[len * T.sizeof .. $];
return ret;
}
//
@trusted uint lookupNamedGroup(String)(NamedGroup[] dict, String name)
{//equal is @system?
import std.conv;
import std.algorithm : map, equal;
auto fnd = assumeSorted!"cmp(a,b) < 0"(map!"a.name"(dict)).lowerBound(name).length;
enforce(fnd < dict.length && equal(dict[fnd].name, name),
text("no submatch named ", name));
return dict[fnd].group;
}
//whether ch is one of unicode newline sequences
//0-arg template due to @@@BUG@@@ 10985
bool endOfLine()(dchar front, bool seenCr)
{
return ((front == '\n') ^ seenCr) || front == '\r'
|| front == NEL || front == LS || front == PS;
}
//
//0-arg template due to @@@BUG@@@ 10985
bool startOfLine()(dchar back, bool seenNl)
{
return ((back == '\r') ^ seenNl) || back == '\n'
|| back == NEL || back == LS || back == PS;
}
//Test if bytecode starting at pc in program 're' can match given codepoint
//Returns: 0 - can't tell, -1 if doesn't match
int quickTestFwd(RegEx)(uint pc, dchar front, const ref RegEx re)
{
static assert(IRL!(IR.OrChar) == 1);//used in code processing IR.OrChar
for(;;)
switch(re.ir[pc].code)
{
case IR.OrChar:
uint len = re.ir[pc].sequence;
uint end = pc + len;
if(re.ir[pc].data != front && re.ir[pc+1].data != front)
{
for(pc = pc+2; pc < end; pc++)
if(re.ir[pc].data == front)
break;
if(pc == end)
return -1;
}
return 0;
case IR.Char:
if(front == re.ir[pc].data)
return 0;
else
return -1;
case IR.Any:
return 0;
case IR.CodepointSet:
if(re.charsets[re.ir[pc].data].scanFor(front))
return 0;
else
return -1;
case IR.GroupStart, IR.GroupEnd:
pc += IRL!(IR.GroupStart);
break;
case IR.Trie:
if(re.tries[re.ir[pc].data][front])
return 0;
else
return -1;
default:
return 0;
}
}
///Exception object thrown in case of errors during regex compilation.
public class RegexException : Exception
{
///
@trusted this(string msg, string file = __FILE__, size_t line = __LINE__)
{//@@@BUG@@@ Exception constructor is not @safe
super(msg, file, line);
}
}
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