--- /dev/null
+/* $Id$
+
+This file is part of libmspstrings
+Copyright © 2007 Mikko Rasa
+Distributed under the LGPL
+*/
+
+#include <stack>
+#include <limits>
+#include <msp/core/except.h>
+#include "formatter.h"
+#include "regex.h"
+
+using namespace std;
+
+namespace {
+
+/** Writes an integer to a Regex code string, in little-endian order. */
+template<typename T>
+void write_int(T n, Msp::Regex::Code &code)
+{
+ for(unsigned i=0; i<sizeof(T); ++i)
+ code += (n>>i*8)&0xFF;
+}
+
+/** Reads an integer from a Regex code stream, in little-endian order. */
+template<typename T>
+T read_int(Msp::Regex::Code::const_iterator &c)
+{
+ T result = 0;
+ for(unsigned i=0; i<sizeof(T); ++i)
+ result += static_cast<unsigned char>(*c++)<<i*8;
+ return result;
+}
+
+}
+
+
+namespace Msp {
+
+Regex::Regex(const string &expr)
+{
+ n_groups = 0;
+ string::const_iterator iter = expr.begin();
+ code = compile(expr, iter, n_groups, false);
+ ++n_groups;
+}
+
+Regex::Code Regex::compile(const string &expr, string::const_iterator &iter, unsigned &group, bool branch)
+{
+ bool has_branches = false;
+ unsigned level = 0;
+ bool escape = false;
+ unsigned bracket = 0;
+ string::const_iterator end;
+ for(end=iter; end!=expr.end(); ++end)
+ {
+ if(escape)
+ escape = false;
+ else if(bracket)
+ {
+ if(bracket==3 && *end==']')
+ bracket = 0;
+ else if(bracket==1 && *end=='^')
+ bracket = 2;
+ else
+ bracket = 3;
+ }
+ else if(*end=='\\')
+ escape = true;
+ else if(*end=='(')
+ ++level;
+ else if(*end==')')
+ {
+ if(level==0)
+ {
+ if(group==0)
+ throw InvalidParameterValue("Unexpected )");
+ else
+ break;
+ }
+ --level;
+ }
+ else if(*end=='|' && level==0)
+ {
+ if(branch)
+ break;
+ else
+ has_branches = true;
+ }
+ else if(*end=='[')
+ bracket = 1;
+ }
+
+ if(level>0)
+ throw InvalidParameterValue("Unmatched (");
+
+ Code result;
+
+ unsigned this_group = group;
+ if(!branch)
+ {
+ result += GROUP_BEGIN;
+ write_int<Index>(this_group, result);
+ }
+
+ const unsigned jump_size = 1+sizeof(Offset);
+
+ if(!has_branches)
+ {
+ for(string::const_iterator i=iter; i!=end;)
+ {
+ Code atom = parse_atom(expr, i, group);
+
+ Count repeat_min = 1;
+ Count repeat_max = 1;
+ parse_repeat(i, repeat_min, repeat_max);
+
+ for(unsigned j=0; j<repeat_min; ++j)
+ result += atom;
+ if(repeat_max==numeric_limits<Count>::max())
+ {
+ if(repeat_min==0)
+ {
+ result += ND_JUMP;
+ write_int<Offset>(atom.size()+jump_size, result);
+ result += atom;
+ }
+ result += ND_JUMP;
+ write_int<Offset>(-(atom.size()+jump_size), result);
+ }
+ else if(repeat_max>repeat_min)
+ {
+ for(unsigned j=repeat_min; j<repeat_max; ++j)
+ {
+ result += ND_JUMP;
+ write_int<Offset>((repeat_max-j)*(atom.size()+jump_size)-jump_size, result);
+ result += atom;
+ }
+ }
+ }
+ }
+ else
+ {
+ list<Code> branches;
+ for(string::const_iterator i=iter;;)
+ {
+ branches.push_back(compile(expr, i, group, true));
+ if(i==end)
+ break;
+ ++i;
+ }
+
+ unsigned n_branches = branches.size();
+
+ Offset offset = (n_branches-1)*jump_size+branches.front().size();
+ for(list<Code>::iterator i=++branches.begin(); i!=branches.end(); ++i)
+ {
+ result += ND_JUMP;
+ write_int<Offset>(offset, result);
+ offset += i->size();
+ }
+
+ for(list<Code>::iterator i=branches.begin(); i!=branches.end();)
+ {
+ result += *i;
+ offset -= i->size()+jump_size;
+ ++i;
+ if(i!=branches.end())
+ {
+ result += JUMP;
+ write_int<Offset>(offset, result);
+ }
+ }
+ }
+
+ if(!branch)
+ {
+ result += GROUP_END;
+ write_int<Index>(this_group, result);
+ }
+
+ iter = end;
+
+ return result;
+}
+
+Regex::Code Regex::parse_atom(const string &expr, string::const_iterator &i, unsigned &group)
+{
+ Code result;
+
+ if(i==expr.end())
+ return result;
+
+ bool flag = false;
+ if(*i=='\\')
+ {
+ if(++i==expr.end())
+ throw InvalidParameterValue("Stray backslash");
+ flag = true;
+ }
+
+ if(!flag)
+ {
+ if(*i=='*' || *i=='{' || *i=='}' || *i=='+' || *i=='?' || *i=='|' || *i==')')
+ throw InvalidParameterValue("Invalid atom");
+ else if(*i=='[')
+ return parse_brackets(expr, i);
+ else if(*i=='.')
+ result += MATCH_ANY;
+ else if(*i=='^')
+ result += MATCH_BEGIN;
+ else if(*i=='$')
+ result += MATCH_END;
+ else if(*i=='(')
+ {
+ ++group;
+ result = compile(expr, ++i, group, false);
+ }
+ else
+ flag = true;
+ }
+
+ if(flag)
+ {
+ result += MATCH_CHAR;
+ result += *i;
+ }
+
+ ++i;
+
+ return result;
+}
+
+bool Regex::parse_repeat(string::const_iterator &i, Count &rmin, Count &rmax)
+{
+ if(*i!='*' && *i!='+' && *i!='?' && *i!='{')
+ return false;
+
+ if(*i=='*' || *i=='+')
+ rmax = numeric_limits<Count>::max();
+ if(*i=='*' || *i=='?')
+ rmin = 0;
+ if(*i=='{')
+ {
+ rmin = 0;
+ for(++i; isdigit(*i); ++i)
+ rmin = rmin*10+(*i-'0');
+
+ if(*i==',')
+ {
+ ++i;
+ if(*i!='}')
+ {
+ rmax = 0;
+ for(; isdigit(*i); ++i)
+ rmax = rmax*10+(*i-'0');
+ if(rmax<rmin)
+ throw InvalidParameterValue("Invalid bound");
+ }
+ else
+ rmax = numeric_limits<Count>::max();
+ }
+ else
+ rmax = rmin;
+ if(*i!='}')
+ throw InvalidParameterValue("Invalid bound");
+ }
+
+ ++i;
+
+ return true;
+}
+
+Regex::Code Regex::parse_brackets(const string &str, string::const_iterator &iter)
+{
+ Code result;
+
+ ++iter;
+ bool neg = false;
+ if(*iter=='^')
+ {
+ neg = true;
+ ++iter;
+ }
+
+ string::const_iterator end = iter;
+ for(; (end!=str.end() && (end==iter || *end!=']')); ++end) ;
+ if(end==str.end())
+ throw InvalidParameterValue("Unmatched '['");
+
+ unsigned char mask[32] = {0};
+ unsigned type = 0;
+ bool range = false;
+ unsigned char first=0, last = 0;
+ for(string::const_iterator i=iter; i!=end; ++i)
+ {
+ unsigned char c = *i;
+ if(range)
+ {
+ last = c;
+ for(unsigned j=first; j<=c; ++j)
+ mask[j>>3] |= 1<<(j&7);
+ range = false;
+ if(type<2)
+ type = 2;
+ }
+ else if(c=='-' && i!=iter && end-i>1)
+ range = true;
+ else
+ {
+ first = c;
+ mask[c>>3] |= 1<<(c&7);
+ if(type==0)
+ type = 1;
+ else
+ type = 3;
+ }
+ }
+
+ if(neg)
+ result += NEGATE;
+
+ if(type==1)
+ {
+ result += MATCH_CHAR;
+ result += first;
+ }
+ else if(type==2)
+ {
+ result += MATCH_RANGE;
+ result += first;
+ result += last;
+ }
+ else
+ {
+ result += MATCH_MASK;
+ result.append(reinterpret_cast<char *>(mask), 32);
+ }
+
+ iter = end;
+ ++iter;
+
+ return result;
+}
+
+RegMatch Regex::match(const string &str) const
+{
+ RegMatch::GroupArray groups(n_groups);
+
+ for(string::const_iterator i=str.begin(); i!=str.end(); ++i)
+ if(run(str, i, groups))
+ return RegMatch(str, groups);
+
+ return RegMatch();
+}
+
+bool Regex::run(const string &str, const string::const_iterator &begin, RegMatch::GroupArray &groups) const
+{
+ bool result = false;
+ list<RunContext> ctx;
+ ctx.push_back(RunContext());
+ ctx.front().citer = code.begin();
+ ctx.front().groups.resize(groups.size());
+
+ for(string::const_iterator i=begin;;)
+ {
+ int c;
+ if(i!=str.end())
+ c = static_cast<unsigned char>(*i);
+ else
+ c = -1;
+
+ for(list<RunContext>::iterator j=ctx.begin(); j!=ctx.end();)
+ {
+ bool terminate = false;
+ bool negate_match = false;
+ for(; j->citer!=code.end();)
+ {
+ Instruction instr = static_cast<Instruction>(*j->citer++);
+
+ if(instr==NEGATE)
+ negate_match = true;
+ else if(instr==JUMP)
+ {
+ Offset offset = read_int<Offset>(j->citer);
+ j->citer += offset;
+ }
+ else if(instr==ND_JUMP)
+ {
+ Offset offset = read_int<Offset>(j->citer);
+ ctx.push_back(*j);
+ ctx.back().citer += offset;
+ }
+ else if(instr==GROUP_BEGIN)
+ {
+ Index n = read_int<Index>(j->citer);
+ if(!j->groups[n].match)
+ j->groups[n].begin = i-str.begin();
+ }
+ else if(instr==GROUP_END)
+ {
+ Index n = read_int<Index>(j->citer);
+ if(!j->groups[n].match)
+ {
+ j->groups[n].match = true;
+ j->groups[n].end = i-str.begin();
+ j->groups[n].length = j->groups[n].end-j->groups[n].begin;
+ }
+
+ if(n==0)
+ {
+ result = true;
+ bool better = false;
+ for(unsigned k=0; (k<groups.size() && !better); ++k)
+ {
+ better = group_compare(j->groups[k], groups[k]);
+ if(group_compare(groups[k], j->groups[k]))
+ break;
+ }
+ if(better)
+ groups = j->groups;
+ }
+ }
+ else
+ {
+ bool match_result = false;
+ bool input_consumed = false;
+ if(instr==MATCH_BEGIN)
+ match_result = (i==str.begin());
+ else if(instr==MATCH_END)
+ match_result = (i==str.end());
+ else if(instr==MATCH_CHAR)
+ {
+ match_result = (c==*j->citer++);
+ input_consumed = true;
+ }
+ else if(instr==MATCH_RANGE)
+ {
+ unsigned char first = *j->citer++;
+ unsigned char last = *j->citer++;
+ match_result = (c>=first && c<=last);
+ input_consumed = true;
+ }
+ else if(instr==MATCH_MASK)
+ {
+ if(c>=0 && c<=0xFF)
+ {
+ unsigned char m = *(j->citer+(c>>3));
+ match_result = m&(1<<(c&7));
+ }
+ input_consumed = true;
+ j->citer += 32;
+ }
+ else if(instr==MATCH_ANY)
+ {
+ match_result = true;
+ input_consumed = true;
+ }
+ else
+ throw Exception("Invalid instruction");
+
+ if(match_result==negate_match)
+ terminate = true;
+ negate_match = false;
+
+ if(input_consumed || terminate)
+ break;
+ }
+ }
+
+ if(terminate || j->citer==code.end())
+ j = ctx.erase(j);
+ else
+ ++j;
+ }
+
+ if(i==str.end() || ctx.empty())
+ break;
+ ++i;
+ }
+
+ return result;
+}
+
+bool Regex::group_compare(const RegMatch::Group &g1, const RegMatch::Group &g2) const
+{
+ if(!g1.match)
+ return false;
+
+ // Any match is better than no match
+ if(!g2.match)
+ return true;
+
+ // Earlier match is better
+ if(g1.begin<g2.begin)
+ return true;
+ if(g2.begin>g2.begin)
+ return false;
+
+ // Longer match at same position is better
+ return g1.end>g2.end;
+}
+
+string Regex::disassemble() const
+{
+ ostringstream ss;
+
+ for(Code::const_iterator i=code.begin(); i!=code.end();)
+ {
+ Code::const_iterator j = i;
+ Offset offset = i-code.begin();
+ string decompiled = disassemble_instruction(i);
+ string bytes;
+ for(; j!=i; ++j)
+ bytes += format(" %02X", static_cast<int>(*j)&0xFF);
+ ss<<Fmt("%3d")<<offset<<':'<<Fmt("%-9s")<<bytes;
+ if(bytes.size()>9)
+ ss<<"\n"<<Fmt("%15s");
+ ss<<" "<<decompiled<<'\n';
+ }
+
+ return ss.str();
+}
+
+string Regex::disassemble_instruction(Code::const_iterator &i) const
+{
+ Instruction instr = static_cast<Instruction>(*i++);
+
+ ostringstream result;
+ switch(instr)
+ {
+ case JUMP:
+ {
+ Offset offset = read_int<Offset>(i);
+ result<<"JUMP "<<Fmt("%+d")<<offset<<" ("<<Fmt("%d")<<i-code.begin()+offset<<')';
+ }
+ break;
+ case ND_JUMP:
+ {
+ Offset offset = read_int<Offset>(i);
+ result<<"ND_JUMP "<<Fmt("%+d")<<offset<<" ("<<Fmt("%d")<<i-code.begin()+offset<<')';
+ }
+ break;
+ case GROUP_BEGIN:
+ result<<"GROUP_BEGIN "<<read_int<Index>(i);
+ break;
+ case GROUP_END:
+ result<<"GROUP_END "<<read_int<Index>(i);
+ break;
+ case NEGATE:
+ result<<"NEGATE";
+ break;
+ case MATCH_BEGIN:
+ result<<"MATCH_BEGIN";
+ break;
+ case MATCH_END:
+ result<<"MATCH_END";
+ break;
+ case MATCH_CHAR:
+ {
+ char c = *i++;
+ result<<"MATCH_CHAR ";
+ if(c>=0x20 && c<=0x7E)
+ result<<'\''<<c<<'\'';
+ else
+ result<<(static_cast<int>(c)&0xFF);
+ }
+ break;
+ case MATCH_RANGE:
+ result<<"MATCH_RANGE "<<(static_cast<int>(*i++)&0xFF);
+ result<<'-'<<(static_cast<int>(*i++)&0xFF);
+ break;
+ case MATCH_MASK:
+ result<<"MATCH_MASK";
+ for(unsigned j=0; j<32; ++j)
+ result<<' '<<Fmt("%02X")<<(static_cast<int>(*i++)&0xFF);
+ break;
+ case MATCH_ANY:
+ result<<"MATCH_ANY";
+ break;
+ default:
+ result<<"UNKNOWN "<<instr;
+ }
+
+ return result.str();
+}
+
+} // namespace Msp
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