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llvm-mirror/lib/Support/TrigramIndex.cpp
Chandler Carruth eb66b33867 Sort the remaining #include lines in include/... and lib/....
I did this a long time ago with a janky python script, but now
clang-format has built-in support for this. I fed clang-format every
line with a #include and let it re-sort things according to the precise
LLVM rules for include ordering baked into clang-format these days.

I've reverted a number of files where the results of sorting includes
isn't healthy. Either places where we have legacy code relying on
particular include ordering (where possible, I'll fix these separately)
or where we have particular formatting around #include lines that
I didn't want to disturb in this patch.

This patch is *entirely* mechanical. If you get merge conflicts or
anything, just ignore the changes in this patch and run clang-format
over your #include lines in the files.

Sorry for any noise here, but it is important to keep these things
stable. I was seeing an increasing number of patches with irrelevant
re-ordering of #include lines because clang-format was used. This patch
at least isolates that churn, makes it easy to skip when resolving
conflicts, and gets us to a clean baseline (again).

llvm-svn: 304787
2017-06-06 11:49:48 +00:00

112 lines
3.2 KiB
C++

//===-- TrigramIndex.cpp - a heuristic for SpecialCaseList ----------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// TrigramIndex implements a heuristic for SpecialCaseList that allows to
// filter out ~99% incoming queries when all regular expressions in the
// SpecialCaseList are simple wildcards with '*' and '.'. If rules are more
// complicated, the check is defeated and it will always pass the queries to a
// full regex.
//
//===----------------------------------------------------------------------===//
#include "llvm/Support/TrigramIndex.h"
#include "llvm/ADT/SmallVector.h"
#include <set>
#include <string>
#include <unordered_map>
using namespace llvm;
static const char RegexAdvancedMetachars[] = "()^$|+?[]\\{}";
static bool isAdvancedMetachar(unsigned Char) {
return strchr(RegexAdvancedMetachars, Char) != nullptr;
}
void TrigramIndex::insert(std::string Regex) {
if (Defeated) return;
std::set<unsigned> Was;
unsigned Cnt = 0;
unsigned Tri = 0;
unsigned Len = 0;
bool Escaped = false;
for (unsigned Char : Regex) {
if (!Escaped) {
// Regular expressions allow escaping symbols by preceding it with '\'.
if (Char == '\\') {
Escaped = true;
continue;
}
if (isAdvancedMetachar(Char)) {
// This is a more complicated regex than we can handle here.
Defeated = true;
return;
}
if (Char == '.' || Char == '*') {
Tri = 0;
Len = 0;
continue;
}
}
if (Escaped && Char >= '1' && Char <= '9') {
Defeated = true;
return;
}
// We have already handled escaping and can reset the flag.
Escaped = false;
Tri = ((Tri << 8) + Char) & 0xFFFFFF;
Len++;
if (Len < 3)
continue;
// We don't want the index to grow too much for the popular trigrams,
// as they are weak signals. It's ok to still require them for the
// rules we have already processed. It's just a small additional
// computational cost.
if (Index[Tri].size() >= 4)
continue;
Cnt++;
if (!Was.count(Tri)) {
// Adding the current rule to the index.
Index[Tri].push_back(Counts.size());
Was.insert(Tri);
}
}
if (!Cnt) {
// This rule does not have remarkable trigrams to rely on.
// We have to always call the full regex chain.
Defeated = true;
return;
}
Counts.push_back(Cnt);
}
bool TrigramIndex::isDefinitelyOut(StringRef Query) const {
if (Defeated)
return false;
std::vector<unsigned> CurCounts(Counts.size());
unsigned Tri = 0;
for (size_t I = 0; I < Query.size(); I++) {
Tri = ((Tri << 8) + Query[I]) & 0xFFFFFF;
if (I < 2)
continue;
const auto &II = Index.find(Tri);
if (II == Index.end())
continue;
for (size_t J : II->second) {
CurCounts[J]++;
// If we have reached a desired limit, we have to look at the query
// more closely by running a full regex.
if (CurCounts[J] >= Counts[J])
return false;
}
}
return true;
}