cmGeneratorExpression: Re-write for multi-stage evaluation

The expressions may be parsed and then cached and evaluated multiple
times.  They are evaluated lazily so that literals such as ',' can be
treated as universal parameter separators, and can be processed from
results without appearing literally, and without interfering with the
parsing/evaluation of the entire expression.

1 files changed, 235 insertions, 0 deletions

diff --git a/Source/cmGeneratorExpressionParser.cxx b/Source/cmGeneratorExpressionParser.cxx
new file mode 100644
index 0000000..2a5cc7a
--- /dev/null
+++ b/Source/cmGeneratorExpressionParser.cxx
@@ -0,0 +1,235 @@
+/*============================================================================
+  CMake - Cross Platform Makefile Generator
+  Copyright 2012 Stephen Kelly <steveire@gmail.com>
+
+  Distributed under the OSI-approved BSD License (the "License");
+  see accompanying file Copyright.txt for details.
+
+  This software is distributed WITHOUT ANY WARRANTY; without even the
+  implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+  See the License for more information.
+============================================================================*/
+
+#include "cmGeneratorExpressionParser.h"
+
+#include "cmGeneratorExpressionEvaluator.h"
+
+//----------------------------------------------------------------------------
+cmGeneratorExpressionParser::cmGeneratorExpressionParser(
+                      const std::vector<cmGeneratorExpressionToken> &tokens)
+  : Tokens(tokens), NestingLevel(0)
+{
+}
+
+//----------------------------------------------------------------------------
+void cmGeneratorExpressionParser::Parse(
+                        std::vector<cmGeneratorExpressionEvaluator*> &result)
+{
+  it = this->Tokens.begin();
+
+  while (this->it != this->Tokens.end())
+    {
+    this->ParseContent(result);
+    }
+}
+
+//----------------------------------------------------------------------------
+static void extendText(std::vector<cmGeneratorExpressionEvaluator*> &result,
+                  std::vector<cmGeneratorExpressionToken>::const_iterator it)
+{
+  if (result.size() > 0
+      && (*(result.end() - 1))->GetType()
+                                  == cmGeneratorExpressionEvaluator::Text)
+    {
+    TextContent *textContent = static_cast<TextContent*>(*(result.end() - 1));
+    textContent->Extend(it->Length);
+    }
+  else
+    {
+    TextContent *textContent = new TextContent(it->Content, it->Length);
+    result.push_back(textContent);
+    }
+}
+
+//----------------------------------------------------------------------------
+static void extendResult(std::vector<cmGeneratorExpressionEvaluator*> &result,
+                const std::vector<cmGeneratorExpressionEvaluator*> &contents)
+{
+  if (result.size() > 0
+      && (*(result.end() - 1))->GetType()
+                                  == cmGeneratorExpressionEvaluator::Text
+      && (*contents.begin())->GetType()
+                                  == cmGeneratorExpressionEvaluator::Text)
+  {
+    TextContent *textContent = static_cast<TextContent*>(*(result.end() - 1));
+    textContent->Extend(
+                  static_cast<TextContent*>(*contents.begin())->GetLength());
+    delete *contents.begin();
+    result.insert(result.end(), contents.begin() + 1, contents.end());
+  } else {
+    result.insert(result.end(), contents.begin(), contents.end());
+  }
+}
+
+//----------------------------------------------------------------------------
+void cmGeneratorExpressionParser::ParseGeneratorExpression(
+                        std::vector<cmGeneratorExpressionEvaluator*> &result)
+{
+  unsigned int nestedLevel = this->NestingLevel;
+  ++this->NestingLevel;
+
+  std::vector<cmGeneratorExpressionToken>::const_iterator startToken
+                                                              = this->it - 1;
+
+  std::vector<cmGeneratorExpressionEvaluator*> identifier;
+  while(this->it->TokenType != cmGeneratorExpressionToken::EndExpression
+      && this->it->TokenType != cmGeneratorExpressionToken::ColonSeparator)
+    {
+    this->ParseContent(identifier);
+    if (this->it == this->Tokens.end())
+      {
+      break;
+      }
+    }
+  if (identifier.empty())
+    {
+    // ERROR
+    }
+
+  if (this->it->TokenType == cmGeneratorExpressionToken::EndExpression)
+    {
+    GeneratorExpressionContent *content = new GeneratorExpressionContent(
+                startToken->Content, this->it->Content
+                                    - startToken->Content
+                                    + this->it->Length);
+    ++this->it;
+    --this->NestingLevel;
+    content->SetIdentifier(identifier);
+    result.push_back(content);
+    return;
+    }
+
+  std::vector<std::vector<cmGeneratorExpressionEvaluator*> > parameters;
+  std::vector<std::vector<cmGeneratorExpressionToken>::const_iterator>
+                                                            commaTokens;
+  std::vector<cmGeneratorExpressionToken>::const_iterator colonToken;
+  if (this->it->TokenType == cmGeneratorExpressionToken::ColonSeparator)
+    {
+    colonToken = this->it;
+    parameters.resize(parameters.size() + 1);
+    ++this->it;
+    while(this->it->TokenType != cmGeneratorExpressionToken::EndExpression)
+      {
+      this->ParseContent(*(parameters.end() - 1));
+      if (this->it->TokenType == cmGeneratorExpressionToken::CommaSeparator)
+        {
+        commaTokens.push_back(this->it);
+        parameters.resize(parameters.size() + 1);
+        ++this->it;
+        }
+      if (this->it == this->Tokens.end())
+        {
+        break;
+        }
+      }
+      if(this->it->TokenType == cmGeneratorExpressionToken::EndExpression)
+        {
+        --this->NestingLevel;
+        ++this->it;
+        }
+      if (parameters.empty())
+        {
+          // ERROR
+        }
+    }
+
+  if (nestedLevel != this->NestingLevel)
+  {
+    // There was a '$<' in the text, but no corresponding '>'. Rebuild to
+    // treat the '$<' as having been plain text, along with the
+    // corresponding : and , tokens that might have been found.
+    extendText(result, startToken);
+    extendResult(result, identifier);
+    if (!parameters.empty())
+      {
+      extendText(result, colonToken);
+
+      typedef std::vector<cmGeneratorExpressionEvaluator*> EvaluatorVector;
+      typedef std::vector<cmGeneratorExpressionToken> TokenVector;
+      std::vector<EvaluatorVector>::const_iterator pit = parameters.begin();
+      const std::vector<EvaluatorVector>::const_iterator pend =
+                                                         parameters.end();
+      std::vector<TokenVector::const_iterator>::const_iterator commaIt =
+                                                         commaTokens.begin();
+      for ( ; pit != pend; ++pit, ++commaIt)
+        {
+        extendResult(result, *pit);
+        if (commaIt != commaTokens.end())
+          {
+          extendText(result, *commaIt);
+          }
+        }
+      }
+    return;
+  }
+
+  int contentLength = ((this->it - 1)->Content
+                    - startToken->Content)
+                    + (this->it - 1)->Length;
+  GeneratorExpressionContent *content = new GeneratorExpressionContent(
+                            startToken->Content, contentLength);
+  content->SetIdentifier(identifier);
+  content->SetParameters(parameters);
+  result.push_back(content);
+}
+
+//----------------------------------------------------------------------------
+void cmGeneratorExpressionParser::ParseContent(
+                        std::vector<cmGeneratorExpressionEvaluator*> &result)
+{
+  switch(this->it->TokenType)
+    {
+    case cmGeneratorExpressionToken::Text:
+    {
+      if (this->NestingLevel == 0)
+        {
+        if (result.size() > 0
+            && (*(result.end() - 1))->GetType()
+                                      == cmGeneratorExpressionEvaluator::Text)
+          {
+          // A comma in 'plain text' could have split text that should
+          // otherwise be continuous. Extend the last text content instead of
+          // creating a new one.
+          TextContent *textContent =
+                              static_cast<TextContent*>(*(result.end() - 1));
+          textContent->Extend(this->it->Length);
+          ++this->it;
+          return;
+          }
+        }
+      cmGeneratorExpressionEvaluator* n = new TextContent(this->it->Content,
+                                                          this->it->Length);
+      result.push_back(n);
+      ++this->it;
+      return ;
+    }
+    case cmGeneratorExpressionToken::BeginExpression:
+      ++this->it;
+      this->ParseGeneratorExpression(result);
+      return;
+    case cmGeneratorExpressionToken::EndExpression:
+    case cmGeneratorExpressionToken::ColonSeparator:
+    case cmGeneratorExpressionToken::CommaSeparator:
+      if (this->NestingLevel == 0)
+        {
+        extendText(result, this->it);
+        }
+      else
+        {
+        // TODO: Unreachable. Assert?
+        }
+      ++this->it;
+      return;
+    }
+  // Unreachable. Assert?
+}