Add pygments2chroma.py script.

_tools/pygments2chroma.py

@@ -0,0 +1,157 @@
+import importlib
+import sys
+import types
+import json
+
+import pystache
+from pygments import lexer as pygments_lexer
+from pygments.token import _TokenType
+
+
+TEMPLATE = r'''
+package lexers
+
+import (
+    . "github.com/alecthomas/chroma" // nolint
+)
+
+// {{upper_name}} lexer.
+var {{upper_name}} = Register(NewLexer(
+    &Config{
+        Name:      "{{name}}",
+        Aliases:   []string{ {{#aliases}}"{{.}}", {{/aliases}} },
+        Filenames: []string{ {{#filenames}}"{{.}}", {{/filenames}} },
+        MimeTypes: []string{ {{#mimetypes}}"{{.}}", {{/mimetypes}} },
+    },
+    Rules{
+{{#tokens}}
+        "{{state}}": {
+            {{#rules}}
+            {{{.}}},
+            {{/rules}}
+        },
+{{/tokens}}
+    },
+))
+'''
+
+
+def go_string(s):
+    if '(?<' in s:
+        warning('perl regex found in %r' % s)
+    if '`' not in s:
+        return '`' + s + '`'
+    return json.dumps(s)
+
+
+def to_camel_case(snake_str):
+    components = snake_str.split('_')
+    return ''.join(x.title() for x in components)
+
+
+def warning(message):
+    print('warning: ' + message, file=sys.stderr)
+
+
+def resolve_emitter(emitter):
+    if isinstance(emitter, types.FunctionType):
+        if repr(emitter).startswith('<function bygroups.'):
+            args = emitter.__closure__[0].cell_contents
+            emitter = 'ByGroups(%s)' % ', '.join(resolve_emitter(e) for e in args)
+        elif repr(emitter).startswith('<function using.'):
+            args = emitter.__closure__[0].cell_contents
+            if isinstance(args, dict):
+                state = 'root'
+                if 'stack' in args:
+                    state = args['stack'][1]
+                    args.pop('stack')
+                assert args == {}, args
+                emitter = 'UsingSelf("%s")' % state
+            elif issubclass(args, pygments_lexer.Lexer):
+                emitter = 'Using(%s, nil)' % args.__name__
+            else:
+                raise ValueError('only support "using" with lexer classes, not %r' % args)
+        else:
+            warning('unsupported emitter function %r' % emitter)
+            emitter = '??'
+    elif isinstance(emitter, _TokenType):
+        emitter = str(emitter).replace('.', '')[5:]
+    elif emitter is None:
+        # This generally only occurs when a lookahead/behind assertion is used, so we just allow it
+        # through.
+        return 'None'
+    else:
+        raise ValueError('unsupported emitter type %r' % emitter)
+    assert isinstance(emitter, str)
+    return emitter
+
+
+def process_state_action(action):
+    if action.startswith('#'):
+        action = action[1:]
+        if action == 'pop':
+            action = 'Pop(1)'
+        elif action == 'push':
+            action = 'Push()'
+        elif action.startswith('push:'):
+            action = 'Push("%s")' % action[5:]
+        else:
+            raise ValueError('unsupported action %r' % (action,))
+    else:
+        action = 'Push("%s")' % action
+    return action
+
+
+def translate_rules(rules):
+    out = []
+    for rule in rules:
+        if isinstance(rule, tuple):
+            regex = rule[0]
+            if isinstance(regex, str):
+                regex = go_string(regex)
+            elif isinstance(regex, pygments_lexer.words):
+                regex = '`%s(?:%s)%s`' % (regex.prefix, '|'.join(regex.words), regex.suffix)
+            else:
+                raise ValueError('expected regex string but got %r' % regex)
+            emitter = resolve_emitter(rule[1])
+            if len(rule) == 2:
+                modifier = 'nil'
+            elif type(rule[2]) is str:
+                modifier = process_state_action(rule[2])
+            elif isinstance(rule[2], pygments_lexer.combined):
+                modifier = 'Combined("%s")' % '", "'.join(rule[2])
+            elif type(rule[2]) is tuple:
+                modifier = 'Push("%s")' % '", "'.join(rule[2])
+            else:
+                raise ValueError('unsupported modifier %r' % (rule[2],))
+            out.append('{{ {}, {}, {} }}'.format(regex, emitter, modifier))
+        elif isinstance(rule, pygments_lexer.include):
+            out.append('Include("{}")'.format(rule))
+        elif isinstance(rule, pygments_lexer.default):
+            out.append('Default({})'.format(process_state_action(rule.state)))
+        else:
+            raise ValueError('unsupported rule %r' % (rule,))
+    return out
+
+
+def main():
+    package_name, symbol_name = sys.argv[1].rsplit(sep=".", maxsplit=1)
+
+    package = importlib.import_module(package_name)
+
+    lexer_cls = getattr(package, symbol_name)
+
+    assert issubclass(lexer_cls, pygments_lexer.RegexLexer), 'can only translate from RegexLexer'
+
+    print(pystache.render(TEMPLATE, {
+        'name': lexer_cls.name,
+        'upper_name': to_camel_case(lexer_cls.name),
+        'aliases': lexer_cls.aliases,
+        'filenames': lexer_cls.filenames,
+        'mimetypes': lexer_cls.mimetypes,
+        'tokens': [{'state': state, 'rules': translate_rules(rules)} for (state, rules) in lexer_cls.get_tokendefs().items()],
+    }))
+
+
+if __name__ == '__main__':
+    main()