[llvm][mustache] Align standalone partial indentation with spec

[ilovepi]

The current implementaion did not correctly handle indentation for
standalone partial tags. It was only applied to lines following a
newline, instead of the first line of a partial's content. This was
fixed by updating the AddIndentation implementaion to prepend the
indentation to the first line of the partial.

[ilovepi]

• [llvm][mustache] Avoid extra allocations in parseSection #159199
• [llvm][mustache] Optimize accessor splitting with a single pass #159198
• [llvm][mustache] Avoid redundant saves in accessor splitting #159197
• [llvm][mustache] Use single pass when tokenizing #159196
• [llvm][mustache] Avoid extra copy for json strings #159195
• [llvm][mustache] Use BumpPtrAllocator to save ASTNodes #159194
• [llvm][mustache] Simplify debug logging #159193
• [llvm][mustache] Fix failing StandaloneIndentation test #159192
• [llvm][mustache] Introduce MustacheContext to simplify mustache APIs #159191
• [llvm][mustache] Use StringRef parameters #159190
• [llvm][mustache] Refactor template rendering #159189
• [llvm][mustache] Refactor tokenizer for clarity #159188
• [llvm][mustache] Support setting delimiters in templates #159187
• [llvm][mustache] Precommit test for Set Delimiter #159186
• [llvm][mustache] Align standalone partial indentation with spec #159185 👈 (View in Graphite)
• [llvm][mustache] Precommit test for StandaloneIndentation #159184
• [llvm][mustache] Add support for Triple Mustache #159183
• [llvm][mustache] Precommit tests for Triple Mustache #159182
• main

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[llvmbot]

@llvm/pr-subscribers-llvm-support

Author: Paul Kirth (ilovepi)

Changes

The current implementaion did not correctly handle indentation for
standalone partial tags. It was only applied to lines following a
newline, instead of the first line of a partial's content. This was
fixed by updating the AddIndentation implementaion to prepend the
indentation to the first line of the partial.

---

Full diff: https://github.com/llvm/llvm-project/pull/159185.diff

2 Files Affected:

• (modified) llvm/lib/Support/Mustache.cpp (+10-4)
• (modified) llvm/unittests/Support/MustacheTest.cpp (+1-1)

diff --git a/llvm/lib/Support/Mustache.cpp b/llvm/lib/Support/Mustache.cpp
index be9cbfd46982f..9c71d6a510056 100644
--- a/llvm/lib/Support/Mustache.cpp
+++ b/llvm/lib/Support/Mustache.cpp
@@ -292,8 +292,7 @@ void stripTokenBefore(SmallVectorImpl<Token> &Tokens, size_t Idx,
   StringRef PrevTokenBody = PrevToken.TokenBody;
   StringRef Unindented = PrevTokenBody.rtrim(" \r\t\v");
   size_t Indentation = PrevTokenBody.size() - Unindented.size();
-  if (CurrentType != Token::Type::Partial)
-    PrevToken.TokenBody = Unindented.str();
+  PrevToken.TokenBody = Unindented.str();
   CurrentToken.setIndentation(Indentation);
 }
 
@@ -425,7 +424,8 @@ class AddIndentationStringStream : public raw_ostream {
 public:
   explicit AddIndentationStringStream(llvm::raw_ostream &WrappedStream,
                                       size_t Indentation)
-      : Indentation(Indentation), WrappedStream(WrappedStream) {
+      : Indentation(Indentation), WrappedStream(WrappedStream),
+        NeedsIndent(true) {
     SetUnbuffered();
   }
 
@@ -434,10 +434,15 @@ class AddIndentationStringStream : public raw_ostream {
     llvm::StringRef Data(Ptr, Size);
     SmallString<0> Indent;
     Indent.resize(Indentation, ' ');
+
     for (char C : Data) {
+      if (NeedsIndent && C != '\n') {
+        WrappedStream << Indent;
+        NeedsIndent = false;
+      }
       WrappedStream << C;
       if (C == '\n')
-        WrappedStream << Indent;
+        NeedsIndent = true;
     }
   }
 
@@ -446,6 +451,7 @@ class AddIndentationStringStream : public raw_ostream {
 private:
   size_t Indentation;
   llvm::raw_ostream &WrappedStream;
+  bool NeedsIndent;
 };
 
 class Parser {
diff --git a/llvm/unittests/Support/MustacheTest.cpp b/llvm/unittests/Support/MustacheTest.cpp
index dadee6bcf7b60..b80c39fb7c5bc 100644
--- a/llvm/unittests/Support/MustacheTest.cpp
+++ b/llvm/unittests/Support/MustacheTest.cpp
@@ -998,7 +998,7 @@ TEST(MustachePartials, StandaloneIndentation) {
   std::string Out;
   raw_string_ostream OS(Out);
   T.render(D, OS);
-  EXPECT_NE("\\\n  |\n  <\n  ->\n  |\n/\n", Out);
+  EXPECT_EQ("\\\n  |\n  <\n  ->\n  |\n/\n", Out);
 }
 
 TEST(MustacheLambdas, BasicInterpolation) {