[mlir] add a simple pygments lexer

[ftynse]

This enables syntax highlighting of MLIR using the Pygments package in Python, which is in turn usable from LaTeX via the minted package.

[llvmbot]

@llvm/pr-subscribers-mlir

Author: Oleksandr "Alex" Zinenko (ftynse)

Changes

This enables syntax highlighting of MLIR using the Pygments package in Python, which is in turn usable from LaTeX via the minted package.

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Full diff: https://github.com/llvm/llvm-project/pull/120942.diff

2 Files Affected:

• (added) mlir/utils/pygments/README.md (+45)
• (added) mlir/utils/pygments/mlir_lexer.py (+37)

diff --git a/mlir/utils/pygments/README.md b/mlir/utils/pygments/README.md
new file mode 100644
index 00000000000000..838faceb01b0fe
--- /dev/null
+++ b/mlir/utils/pygments/README.md
@@ -0,0 +1,45 @@
+## Pygments Lexer for MLIR
+
+This file contains a simple Pygments lexer configuration for MLIR, derived from
+the version used in the original CGO paper. Pygments allows for advanced
+configurable syntax highlighting of any code. This lexer is known to be
+incomplete and support mostly core IR with a subset of built-in types.
+Additions and customizations are welcome.
+
+### Standalone Usage
+
+Install Pygments, e.g., by running `pip install Pygments` or a Python package
+manager of your choosing. Use the standalone `pygmentize` command by
+instructing it to load the custom lexer:
+
+```
+pygmentize -l /path/to/mlir_lexer.py:MlirLexer -x myfile.mlir
+```
+
+This will produce highlighted output in the terminal. Other output formats are
+available, see Pygments [documentation](https://pygments.org/docs/) for more
+information.
+
+### LaTeX Usage
+
+First, make sure your distribution includes the `minted` package and list in
+the preamble.
+
+```latex
+\usepackage{minted}
+```
+
+Place the `mlir_lexer.py` in a place where the `latex` binary can find it,
+typically in the working directory next to the main `.tex` file. Note that you
+will have to invoke `latex` with the `-shell-escape` flag. See the `minted` 
+package [documentation](https://ctan.org/pkg/minted?lang=en) for more
+information.
+
+Leverage the custom lexer facility of `minted` to use this lexer in your
+document as:
+
+```latex
+\begin{minted}{mlir_lexer.py:MlirLexer -x}
+   ... your code here ...
+\end{minted}
+```
diff --git a/mlir/utils/pygments/mlir_lexer.py b/mlir/utils/pygments/mlir_lexer.py
new file mode 100644
index 00000000000000..d078b4502e6deb
--- /dev/null
+++ b/mlir/utils/pygments/mlir_lexer.py
@@ -0,0 +1,37 @@
+# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+# See https://llvm.org/LICENSE.txt for license information.
+# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+
+from pygments.lexer import RegexLexer
+from pygments.token import *
+
+class MlirLexer(RegexLexer):
+    name = 'MLIR'
+    aliases = ['mlir']
+    filenames = ['*.mlir']
+
+    tokens = {
+        'root': [
+            (r'%[a-zA-Z0-9_]+', Name.Variable),
+            (r'@[a-zA-Z_][a-zA-Z0-9_]+', Name.Function),
+            (r'\^[a-zA-Z0-9_]+', Name.Label),
+            (r'#[a-zA-Z0-9_]+', Name.Constant),
+            (r'![a-zA-Z0-9_]+', Keyword.Type),
+            (r'[a-zA-Z_][a-zA-Z0-9_]*\.', Name.Entity),
+            (r'memref[^.]', Keyword.Type),
+            (r'index', Keyword.Type),
+            (r'i[0-9]+', Keyword.Type),
+            (r'f[0-9]+', Keyword.Type),
+            (r'[0-9]+', Number.Integer),
+            (r'[0-9]*\.[0-9]*', Number.Float),
+            (r'"[^"]*"', String.Double),
+            (r'affine_map', Keyword.Reserved),
+            # TODO: this should be within affine maps only
+            (r'\+-\*\/', Operator),
+            (r'floordiv', Operator.Word),
+            (r'ceildiv', Operator.Word),
+            (r'mod', Operator.Word),
+            (r'()\[\]<>,{}', Punctuation),
+            (r'\/\/.*\n', Comment.Single),
+        ]
+    }

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