1 files changed, 66 insertions, 0 deletions
diff --git a/projects/hackc/tokens.py b/projects/hackc/tokens.py
new file mode 100644
index 0000000..7ae37ce
--- /dev/null
+++ b/projects/hackc/tokens.py
@@ -0,0 +1,66 @@
+import re
+
+KEYWORDS = [
+    "class",
+    "constructor",
+    "function",
+    "method",
+    "field",
+    "static",
+    "var",
+    "int",
+    "char",
+    "boolean",
+    "void",
+    "true",
+    "false",
+    "null",
+    "this",
+    "let",
+    "do",
+    "if",
+    "else",
+    "while",
+    "return",
+]
+SYMBOLS = "{}()[].,;+-*/&|<>=~"
+TOKEN_TYPES = ["keyword", "symbol", "integer", "string", "identifier"]
+
+class Token:
+    def __init__(self, type: str, token: str, line_no: int, column: int):
+        """A token in JACK."""
+        self.type = type
+        self.token = token
+        self.line_no = line_no
+        self.column = column
+
+    @classmethod
+    def from_line(cls, line: str, line_no: int, column: int):
+        """Extract first token from line and return it as an instance of Token."""
+        if not line:
+            return None
+
+        if line[0] in SYMBOLS:
+            return Token("symbol", line[0], line_no, column)
+
+        int_match = re.match("([0-9]+)", line)
+        if int_match is not None:
+            return Token("integer", int_match.group(1), line_no, column)
+
+        str_match = re.match('(".*")', line)
+        if str_match is not None:
+            return Token("string", str_match.group(1), line_no, column)
+
+        # keyword or identifier
+        kwid_match = re.match("([_A-Za-z][_A-Za-z0-9]*)", line)
+        if kwid_match is not None:
+            kwid = kwid_match.group(1)
+            type = "identifier"
+            if kwid in KEYWORDS:
+                type = "keyword"
+            return Token(type, kwid, line_no, column)
+
+        return None
+
+    def length(self) -> int:
+        return len(self.token)