Add a parser for GCC-style depfiles

Introduce the function cmReadGccDepfile that parses a GCC-style depfile
and returns its content. The implementation uses a lexer that is
modeled after the re2c implementation in Ninja.

The sample files of the autotest have been created with gcc 8.3.0.

This depfile reader is to be used by the Autogen facility to make use
of the depfiles that are generated by Qt's meta object compiler.

1 files changed, 126 insertions, 0 deletions

diff --git a/Source/cmGccDepfileLexerHelper.cxx b/Source/cmGccDepfileLexerHelper.cxx
new file mode 100644
index 0000000..957896f
--- /dev/null
+++ b/Source/cmGccDepfileLexerHelper.cxx
@@ -0,0 +1,126 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#include "cmGccDepfileLexerHelper.h"
+
+#include <cstdio>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "cmGccDepfileReaderTypes.h"
+
+#include "LexerParser/cmGccDepfileLexer.h"
+
+#ifdef _WIN32
+#  include "cmsys/Encoding.h"
+#endif
+
+bool cmGccDepfileLexerHelper::readFile(const char* filePath)
+{
+#ifdef _WIN32
+  wchar_t* wpath = cmsysEncoding_DupToWide(filePath);
+  FILE* file = _wfopen(wpath, L"rb");
+  free(wpath);
+#else
+  FILE* file = fopen(filePath, "r");
+#endif
+  if (!file) {
+    return false;
+  }
+  newEntry();
+  yyscan_t scanner;
+  cmGccDepfile_yylex_init(&scanner);
+  cmGccDepfile_yyset_extra(this, scanner);
+  cmGccDepfile_yyrestart(file, scanner);
+  cmGccDepfile_yylex(scanner);
+  cmGccDepfile_yylex_destroy(scanner);
+  sanitizeContent();
+  fclose(file);
+  return true;
+}
+
+void cmGccDepfileLexerHelper::newEntry()
+{
+  this->HelperState = State::Rule;
+  this->Content.emplace_back();
+  newRule();
+}
+
+void cmGccDepfileLexerHelper::newRule()
+{
+  auto& entry = this->Content.back();
+  if (entry.rules.empty() || !entry.rules.back().empty()) {
+    entry.rules.emplace_back();
+  }
+}
+
+void cmGccDepfileLexerHelper::newDependency()
+{
+  // printf("NEW DEP\n");
+  this->HelperState = State::Dependency;
+  if (this->Content.back().paths.empty() ||
+      !this->Content.back().paths.back().empty()) {
+    this->Content.back().paths.emplace_back();
+  }
+}
+
+void cmGccDepfileLexerHelper::newRuleOrDependency()
+{
+  if (this->HelperState == State::Rule) {
+    newRule();
+  } else {
+    newDependency();
+  }
+}
+
+void cmGccDepfileLexerHelper::addToCurrentPath(const char* s)
+{
+  if (this->Content.empty()) {
+    return;
+  }
+  cmGccStyleDependency* dep = &this->Content.back();
+  std::string* dst = nullptr;
+  switch (this->HelperState) {
+    case State::Rule: {
+      if (dep->rules.empty()) {
+        return;
+      }
+      dst = &dep->rules.back();
+    } break;
+    case State::Dependency: {
+      if (dep->paths.empty()) {
+        return;
+      }
+      dst = &dep->paths.back();
+    } break;
+  }
+  dst->append(s);
+}
+
+void cmGccDepfileLexerHelper::sanitizeContent()
+{
+  for (auto it = this->Content.begin(); it != this->Content.end();) {
+    // Remove empty rules
+    for (auto rit = it->rules.begin(); rit != it->rules.end();) {
+      if (rit->empty()) {
+        rit = it->rules.erase(rit);
+      } else {
+        ++rit;
+      }
+    }
+    // Remove the entry if rules are empty
+    if (it->rules.empty()) {
+      it = this->Content.erase(it);
+    } else {
+      // Remove empty paths
+      for (auto pit = it->paths.begin(); pit != it->paths.end();) {
+        if (pit->empty()) {
+          pit = it->paths.erase(pit);
+        } else {
+          ++pit;
+        }
+      }
+      ++it;
+    }
+  }
+}