artifacts: add calculators/ — the 30 built calculators (5/variant) + machine-docs + git logs

calculators/builder-solo/run-05/calc/lexer.py

@@ -0,0 +1,65 @@
+"""Lexer for arithmetic expressions."""
+
+from dataclasses import dataclass
+from typing import Union
+
+
+class LexError(Exception):
+    pass
+
+
+@dataclass
+class Token:
+    kind: str
+    value: Union[int, float, None]
+
+    def __repr__(self):
+        return f"{self.kind}({self.value!r})"
+
+
+_SINGLE = {
+    '+': 'PLUS',
+    '-': 'MINUS',
+    '*': 'STAR',
+    '/': 'SLASH',
+    '(': 'LPAREN',
+    ')': 'RPAREN',
+}
+
+EOF = Token('EOF', None)
+
+
+def tokenize(src: str) -> list:
+    tokens = []
+    i = 0
+    while i < len(src):
+        ch = src[i]
+
+        if ch in ' \t\r\n':
+            i += 1
+            continue
+
+        if ch in _SINGLE:
+            tokens.append(Token(_SINGLE[ch], ch))
+            i += 1
+            continue
+
+        if ch.isdigit() or ch == '.':
+            j = i
+            has_dot = False
+            while j < len(src) and (src[j].isdigit() or (src[j] == '.' and not has_dot)):
+                if src[j] == '.':
+                    has_dot = True
+                j += 1
+            raw = src[i:j]
+            if raw == '.':
+                raise LexError(f"Invalid character '.' at position {i}")
+            value = float(raw) if has_dot else int(raw)
+            tokens.append(Token('NUMBER', value))
+            i = j
+            continue
+
+        raise LexError(f"Invalid character {ch!r} at position {i}")
+
+    tokens.append(EOF)
+    return tokens