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

calculators/builder-adversary-lean/run-04/calc/parser.py

@@ -0,0 +1,123 @@
+from dataclasses import dataclass
+from typing import Any
+
+from calc.lexer import Token
+
+
+class ParseError(Exception):
+    pass
+
+
+@dataclass
+class Num:
+    value: Any
+
+    def __repr__(self):
+        return f"Num({self.value!r})"
+
+
+@dataclass
+class BinOp:
+    op: str
+    left: Any
+    right: Any
+
+    def __repr__(self):
+        return f"BinOp({self.op!r}, {self.left!r}, {self.right!r})"
+
+
+@dataclass
+class Unary:
+    op: str
+    operand: Any
+
+    def __repr__(self):
+        return f"Unary({self.op!r}, {self.operand!r})"
+
+
+class _Parser:
+    def __init__(self, tokens: list):
+        self._tokens = tokens
+        self._pos = 0
+
+    def _peek(self) -> Token:
+        return self._tokens[self._pos]
+
+    def _consume(self, kind: str) -> Token:
+        tok = self._peek()
+        if tok.kind != kind:
+            raise ParseError(
+                f"expected {kind!r} but got {tok.kind!r} ({tok.value!r})"
+            )
+        self._pos += 1
+        return tok
+
+    def _advance(self) -> Token:
+        tok = self._tokens[self._pos]
+        self._pos += 1
+        return tok
+
+    def parse(self):
+        node = self._expr()
+        tok = self._peek()
+        if tok.kind != 'EOF':
+            raise ParseError(
+                f"unexpected token {tok.kind!r} ({tok.value!r}) after expression"
+            )
+        return node
+
+    # expr := term (('+' | '-') term)*
+    def _expr(self):
+        node = self._term()
+        while self._peek().kind in ('PLUS', 'MINUS'):
+            op = self._advance().value
+            right = self._term()
+            node = BinOp(op, node, right)
+        return node
+
+    # term := unary (('*' | '/') unary)*
+    def _term(self):
+        node = self._unary()
+        while self._peek().kind in ('STAR', 'SLASH'):
+            op = self._advance().value
+            right = self._unary()
+            node = BinOp(op, node, right)
+        return node
+
+    # unary := '-' unary | primary
+    def _unary(self):
+        if self._peek().kind == 'MINUS':
+            op = self._advance().value
+            operand = self._unary()
+            return Unary(op, operand)
+        return self._primary()
+
+    # primary := NUMBER | '(' expr ')'
+    def _primary(self):
+        tok = self._peek()
+        if tok.kind == 'NUMBER':
+            self._advance()
+            return Num(tok.value)
+        if tok.kind == 'LPAREN':
+            self._advance()
+            node = self._expr()
+            self._consume('RPAREN')
+            return node
+        raise ParseError(
+            f"unexpected token {tok.kind!r} ({tok.value!r}); expected number or '('"
+        )
+
+
+def parse(tokens: list):
+    """Parse a token list produced by `calc.lexer.tokenize` into an AST.
+
+    Returns one of:
+      Num(value)
+      BinOp(op, left, right)   op in {'+', '-', '*', '/'}
+      Unary(op, operand)       op == '-'
+
+    Raises ParseError on malformed input.
+    """
+    if not tokens or (len(tokens) == 1 and tokens[0].kind == 'EOF'):
+        raise ParseError("empty input")
+    return _Parser(tokens).parse()