Add default values for function parameter chunks

Append optional chunks with their default values. For example:
before - "int i", after - "int i = 10"

Patch by Ivan Donchevskii!
    
Differential Revision: https://reviews.llvm.org/D33644

llvm-svn: 308433

1 files changed, 40 insertions, 3 deletions

diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index 3a53f251b09..f4f42e87da3 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -2398,6 +2398,37 @@ formatBlockPlaceholder(const PrintingPolicy &Policy, const NamedDecl *BlockDecl,
   return Result;
 }
 
+static std::string GetDefaultValueString(const ParmVarDecl *Param,
+                                         const SourceManager &SM,
+                                         const LangOptions &LangOpts) {
+  const Expr *defaultArg = Param->getDefaultArg();
+  if (!defaultArg)
+    return "";
+  const SourceRange SrcRange = defaultArg->getSourceRange();
+  CharSourceRange CharSrcRange = CharSourceRange::getTokenRange(SrcRange);
+  bool Invalid = CharSrcRange.isInvalid();
+  if (Invalid)
+    return "";
+  StringRef srcText = Lexer::getSourceText(CharSrcRange, SM, LangOpts, &Invalid);
+  if (Invalid)
+    return "";
+
+  if (srcText.empty() || srcText == "=") {
+    // Lexer can't determine the value.
+    // This happens if the code is incorrect (for example class is forward declared).
+    return "";
+  }
+  std::string DefValue{srcText};
+  // FIXME: remove this check if the Lexer::getSourceText value is fixed and
+  // this value always has (or always does not have) '=' in front of it
+  if (DefValue.at(0) != '=') {
+    // If we don't have '=' in front of value.
+    // Lexer returns built-in types values without '=' and user-defined types values with it.
+    return " = " + DefValue;
+  }
+  return " " + DefValue;
+}
+
 /// \brief Add function parameter chunks to the given code completion string.
 static void AddFunctionParameterChunks(Preprocessor &PP,
                                        const PrintingPolicy &Policy,
@@ -2431,6 +2462,8 @@ static void AddFunctionParameterChunks(Preprocessor &PP,
     
     // Format the placeholder string.
     std::string PlaceholderStr = FormatFunctionParameter(Policy, Param);
+    if (Param->hasDefaultArg())
+      PlaceholderStr += GetDefaultValueString(Param, PP.getSourceManager(), PP.getLangOpts());
 
     if (Function->isVariadic() && P == N - 1)
       PlaceholderStr += ", ...";
@@ -3012,10 +3045,14 @@ static void AddOverloadParameterChunks(ASTContext &Context,
 
     // Format the placeholder string.
     std::string Placeholder;
-    if (Function)
-      Placeholder = FormatFunctionParameter(Policy, Function->getParamDecl(P));
-    else
+    if (Function) {
+      const ParmVarDecl *Param = Function->getParamDecl(P);
+      Placeholder = FormatFunctionParameter(Policy, Param);
+      if (Param->hasDefaultArg())
+        Placeholder += GetDefaultValueString(Param, Context.getSourceManager(), Context.getLangOpts());
+    } else {
       Placeholder = Prototype->getParamType(P).getAsString(Policy);
+    }
 
     if (P == CurrentArg)
       Result.AddCurrentParameterChunk(