1239310Sdim//===- StringMatcher.cpp - Generate a matcher for input strings -----------===// 2239310Sdim// 3239310Sdim// The LLVM Compiler Infrastructure 4239310Sdim// 5239310Sdim// This file is distributed under the University of Illinois Open Source 6239310Sdim// License. See LICENSE.TXT for details. 7239310Sdim// 8239310Sdim//===----------------------------------------------------------------------===// 9239310Sdim// 10239310Sdim// This file implements the StringMatcher class. 11239310Sdim// 12239310Sdim//===----------------------------------------------------------------------===// 13239310Sdim 14239310Sdim#include "llvm/TableGen/StringMatcher.h" 15239310Sdim#include "llvm/Support/raw_ostream.h" 16239310Sdim#include <map> 17239310Sdimusing namespace llvm; 18239310Sdim 19239310Sdim/// FindFirstNonCommonLetter - Find the first character in the keys of the 20239310Sdim/// string pairs that is not shared across the whole set of strings. All 21239310Sdim/// strings are assumed to have the same length. 22239310Sdimstatic unsigned 23239310SdimFindFirstNonCommonLetter(const std::vector<const 24239310Sdim StringMatcher::StringPair*> &Matches) { 25239310Sdim assert(!Matches.empty()); 26239310Sdim for (unsigned i = 0, e = Matches[0]->first.size(); i != e; ++i) { 27239310Sdim // Check to see if letter i is the same across the set. 28239310Sdim char Letter = Matches[0]->first[i]; 29239310Sdim 30239310Sdim for (unsigned str = 0, e = Matches.size(); str != e; ++str) 31239310Sdim if (Matches[str]->first[i] != Letter) 32239310Sdim return i; 33239310Sdim } 34239310Sdim 35239310Sdim return Matches[0]->first.size(); 36239310Sdim} 37239310Sdim 38239310Sdim/// EmitStringMatcherForChar - Given a set of strings that are known to be the 39239310Sdim/// same length and whose characters leading up to CharNo are the same, emit 40239310Sdim/// code to verify that CharNo and later are the same. 41239310Sdim/// 42239310Sdim/// \return - True if control can leave the emitted code fragment. 43239310Sdimbool StringMatcher:: 44239310SdimEmitStringMatcherForChar(const std::vector<const StringPair*> &Matches, 45239310Sdim unsigned CharNo, unsigned IndentCount) const { 46239310Sdim assert(!Matches.empty() && "Must have at least one string to match!"); 47239310Sdim std::string Indent(IndentCount*2+4, ' '); 48239310Sdim 49239310Sdim // If we have verified that the entire string matches, we're done: output the 50239310Sdim // matching code. 51239310Sdim if (CharNo == Matches[0]->first.size()) { 52239310Sdim assert(Matches.size() == 1 && "Had duplicate keys to match on"); 53239310Sdim 54239310Sdim // If the to-execute code has \n's in it, indent each subsequent line. 55239310Sdim StringRef Code = Matches[0]->second; 56239310Sdim 57239310Sdim std::pair<StringRef, StringRef> Split = Code.split('\n'); 58239310Sdim OS << Indent << Split.first << "\t // \"" << Matches[0]->first << "\"\n"; 59239310Sdim 60239310Sdim Code = Split.second; 61239310Sdim while (!Code.empty()) { 62239310Sdim Split = Code.split('\n'); 63239310Sdim OS << Indent << Split.first << "\n"; 64239310Sdim Code = Split.second; 65239310Sdim } 66239310Sdim return false; 67239310Sdim } 68239310Sdim 69239310Sdim // Bucket the matches by the character we are comparing. 70239310Sdim std::map<char, std::vector<const StringPair*> > MatchesByLetter; 71239310Sdim 72239310Sdim for (unsigned i = 0, e = Matches.size(); i != e; ++i) 73239310Sdim MatchesByLetter[Matches[i]->first[CharNo]].push_back(Matches[i]); 74239310Sdim 75239310Sdim 76239310Sdim // If we have exactly one bucket to match, see how many characters are common 77239310Sdim // across the whole set and match all of them at once. 78239310Sdim if (MatchesByLetter.size() == 1) { 79239310Sdim unsigned FirstNonCommonLetter = FindFirstNonCommonLetter(Matches); 80239310Sdim unsigned NumChars = FirstNonCommonLetter-CharNo; 81239310Sdim 82239310Sdim // Emit code to break out if the prefix doesn't match. 83239310Sdim if (NumChars == 1) { 84239310Sdim // Do the comparison with if (Str[1] != 'f') 85239310Sdim // FIXME: Need to escape general characters. 86239310Sdim OS << Indent << "if (" << StrVariableName << "[" << CharNo << "] != '" 87239310Sdim << Matches[0]->first[CharNo] << "')\n"; 88239310Sdim OS << Indent << " break;\n"; 89239310Sdim } else { 90239310Sdim // Do the comparison with if memcmp(Str.data()+1, "foo", 3). 91239310Sdim // FIXME: Need to escape general strings. 92239310Sdim OS << Indent << "if (memcmp(" << StrVariableName << ".data()+" << CharNo 93239310Sdim << ", \"" << Matches[0]->first.substr(CharNo, NumChars) << "\", " 94239310Sdim << NumChars << "))\n"; 95239310Sdim OS << Indent << " break;\n"; 96239310Sdim } 97239310Sdim 98239310Sdim return EmitStringMatcherForChar(Matches, FirstNonCommonLetter, IndentCount); 99239310Sdim } 100239310Sdim 101239310Sdim // Otherwise, we have multiple possible things, emit a switch on the 102239310Sdim // character. 103239310Sdim OS << Indent << "switch (" << StrVariableName << "[" << CharNo << "]) {\n"; 104239310Sdim OS << Indent << "default: break;\n"; 105239310Sdim 106239310Sdim for (std::map<char, std::vector<const StringPair*> >::iterator LI = 107239310Sdim MatchesByLetter.begin(), E = MatchesByLetter.end(); LI != E; ++LI) { 108239310Sdim // TODO: escape hard stuff (like \n) if we ever care about it. 109239310Sdim OS << Indent << "case '" << LI->first << "':\t // " 110239310Sdim << LI->second.size() << " string"; 111239310Sdim if (LI->second.size() != 1) OS << 's'; 112239310Sdim OS << " to match.\n"; 113239310Sdim if (EmitStringMatcherForChar(LI->second, CharNo+1, IndentCount+1)) 114239310Sdim OS << Indent << " break;\n"; 115239310Sdim } 116239310Sdim 117239310Sdim OS << Indent << "}\n"; 118239310Sdim return true; 119239310Sdim} 120239310Sdim 121239310Sdim 122239310Sdim/// Emit - Top level entry point. 123239310Sdim/// 124239310Sdimvoid StringMatcher::Emit(unsigned Indent) const { 125239310Sdim // If nothing to match, just fall through. 126239310Sdim if (Matches.empty()) return; 127239310Sdim 128239310Sdim // First level categorization: group strings by length. 129239310Sdim std::map<unsigned, std::vector<const StringPair*> > MatchesByLength; 130239310Sdim 131239310Sdim for (unsigned i = 0, e = Matches.size(); i != e; ++i) 132239310Sdim MatchesByLength[Matches[i].first.size()].push_back(&Matches[i]); 133239310Sdim 134239310Sdim // Output a switch statement on length and categorize the elements within each 135239310Sdim // bin. 136239310Sdim OS.indent(Indent*2+2) << "switch (" << StrVariableName << ".size()) {\n"; 137239310Sdim OS.indent(Indent*2+2) << "default: break;\n"; 138239310Sdim 139239310Sdim for (std::map<unsigned, std::vector<const StringPair*> >::iterator LI = 140239310Sdim MatchesByLength.begin(), E = MatchesByLength.end(); LI != E; ++LI) { 141239310Sdim OS.indent(Indent*2+2) << "case " << LI->first << ":\t // " 142239310Sdim << LI->second.size() 143239310Sdim << " string" << (LI->second.size() == 1 ? "" : "s") << " to match.\n"; 144239310Sdim if (EmitStringMatcherForChar(LI->second, 0, Indent)) 145239310Sdim OS.indent(Indent*2+4) << "break;\n"; 146239310Sdim } 147239310Sdim 148239310Sdim OS.indent(Indent*2+2) << "}\n"; 149239310Sdim} 150