From 732ef5e9787e618ead3a18f9f6aa2ed1f03f1670 Mon Sep 17 00:00:00 2001
From: Melody Horn <melody@boringcactus.com>
Date: Wed, 14 Oct 2020 17:44:38 -0600
Subject: throw early draft of parser into the world

---
 crowbar_reference_compiler/scanner.py | 76 +++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)
 create mode 100644 crowbar_reference_compiler/scanner.py

(limited to 'crowbar_reference_compiler/scanner.py')

diff --git a/crowbar_reference_compiler/scanner.py b/crowbar_reference_compiler/scanner.py
new file mode 100644
index 0000000..fff8c35
--- /dev/null
+++ b/crowbar_reference_compiler/scanner.py
@@ -0,0 +1,76 @@
+from dataclasses import dataclass
+from typing import Optional, overload, List, Union
+
+import regex as re  # type: ignore
+
+
+@dataclass
+class Token:
+    type: str
+    data: Optional[str] = None
+
+    def __repr__(self) -> str:
+        if self.data is not None:
+            return "{}: {}".format(self.type, repr(self.data))
+        else:
+            return repr(self.type)
+
+
+class GenerousTokenList(List[Token]):
+    def __getitem__(self, i):
+        try:
+            return super(GenerousTokenList, self).__getitem__(i)
+        except IndexError:
+            return Token('')
+
+
+KEYWORD = re.compile("bool|break|case|char|const|continue|default|do|double|else|enum|extern|float|for|function|if|include|int|long|return|short|signed|sizeof|struct|switch|typedef|unsigned|void|while")
+IDENTIFIER = re.compile(r"[\p{L}\p{Pc}\p{Cf}\p{Sk}\p{Mn}][\p{L}\p{Pc}\p{Cf}\p{Sk}\p{Mn}\p{N}]*")
+CONSTANT = re.compile(r"""([0-9_]+)|(0[bB][01_]+)|(0[xX][0-9a-fA-F_]+)|([0-9_]+(\.[0-9_]+|[eE][0-9_]+|\.[0-9_]+[eE][0-9_]+))|('([^\'\\]|\\'|\\"|\\\\|\\r|\\n|\\t|\\0|\\x[0-9a-fA-F]{2}|\\u[0-9a-fA-F]{4}|\\U[0-9a-fA-F]{8})')""")
+STRING_LITERAL = re.compile(r'''"([^\\"]|\\'|\\"|\\\\|\\r|\\n|\\t|\\0|\\x[0-9a-fA-F]{2}|\\u[0-9a-fA-F]{4}|\\U[0-9a-fA-F]{8})*"''')
+PUNCTUATOR = re.compile(r"->|\+\+|--|>>|<<|<=|>=|&&|\|\||[=!+\-*/%&|^]=|[\[\](){}.,+\-*/%;!&|^~><=]")
+WHITESPACE = re.compile(r"[\p{Zs}\p{Cc}]+")
+COMMENT = re.compile(r"(//[^\n]*\n)|(/\*.*?\*/)", re.DOTALL)
+
+
+def scan(code):
+    result = []
+    remaining = code
+
+    while len(remaining) > 0:
+        match = COMMENT.match(remaining)
+        if match:
+            remaining = remaining[match.end():]
+            continue
+        match = WHITESPACE.match(remaining)
+        if match:
+            remaining = remaining[match.end():]
+            continue
+        match = KEYWORD.match(remaining)
+        if match:
+            result.append(Token(match.group()))
+            remaining = remaining[match.end():]
+            continue
+        match = IDENTIFIER.match(remaining)
+        if match:
+            result.append(Token('identifier', match.group()))
+            remaining = remaining[match.end():]
+            continue
+        match = CONSTANT.match(remaining)
+        if match:
+            result.append(Token('constant', match.group()))
+            remaining = remaining[match.end():]
+            continue
+        match = STRING_LITERAL.match(remaining)
+        if match:
+            result.append(Token('string_literal', match.group()))
+            remaining = remaining[match.end():]
+            continue
+        match = PUNCTUATOR.match(remaining)
+        if match:
+            result.append(Token(match.group()))
+            remaining = remaining[match.end():]
+            continue
+        raise ValueError("unrecognized code in scanner: {}".format(repr(remaining[:20])))
+
+    return GenerousTokenList(result)
-- 
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