[YAMLIO] Make line-wrapping configurable and test it.

Summary:
We would wrap flow mappings and sequences when they go over a hardcoded 70
characters limit. Make the wrapping column configurable (and default to 70
co the change should be NFC for current users). Passing 0 allows to completely
suppress the wrapping which makes it easier to handle in tools like FileCheck.

Reviewers: bogner

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D10109

llvm-svn: 238584

1 files changed, 11 insertions, 3 deletions

diff --git a/llvm/docs/YamlIO.rst b/llvm/docs/YamlIO.rst
index aa4bae35d1a..f0baeb4c69d 100644
--- a/llvm/docs/YamlIO.rst
+++ b/llvm/docs/YamlIO.rst
@@ -798,6 +798,8 @@ add "static const bool flow = true;". For instance:
       static const bool flow = true;
     }
 
+Flow mappings are subject to line wrapping according to the Output object
+configuration.
 
 Sequence
 ========
@@ -845,6 +847,8 @@ With the above, if you used MyList as the data type in your native data
 structures, then when converted to YAML, a flow sequence of integers 
 will be used (e.g. [ 10, -3, 4 ]).
 
+Flow sequences are subject to line wrapping according to the Output object
+configuration.
 
 Utility Macros
 --------------
@@ -908,14 +912,14 @@ Output
 
 The llvm::yaml::Output class is used to generate a YAML document from your 
 in-memory data structures, using traits defined on your data types.  
-To instantiate an Output object you need an llvm::raw_ostream, and optionally 
-a context pointer:
+To instantiate an Output object you need an llvm::raw_ostream, an optional 
+context pointer and an optional wrapping column:
 
 .. code-block:: c++
 
       class Output : public IO {
       public:
-        Output(llvm::raw_ostream &, void *context=NULL);
+        Output(llvm::raw_ostream &, void *context = NULL, int WrapColumn = 70);
     
 Once you have an Output object, you can use the C++ stream operator on it
 to write your native data as YAML. One thing to recall is that a YAML file
@@ -924,6 +928,10 @@ streaming as YAML is a mapping, scalar, or sequence, then Output assumes you
 are generating one document and wraps the mapping output 
 with  "``---``" and trailing "``...``".  
 
+The WrapColumn parameter will cause the flow mappings and sequences to
+line-wrap when they go over the supplied column. Pass 0 to completely
+suppress the wrapping.
+
 .. code-block:: c++
    
     using llvm::yaml::Output;