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

calculators/builder-adversary-min/run-03/calc/parser.py

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+from dataclasses import dataclass
+from typing import Union, List
+from calc.lexer import Token
+
+
+class ParseError(Exception):
+    pass
+
+
+@dataclass
+class Num:
+    value: Union[int, float]
+
+    def __repr__(self):
+        return f"Num({self.value!r})"
+
+
+@dataclass
+class BinOp:
+    op: str
+    left: 'Node'
+    right: 'Node'
+
+    def __repr__(self):
+        return f"BinOp({self.op!r}, {self.left!r}, {self.right!r})"
+
+
+@dataclass
+class Unary:
+    op: str
+    operand: 'Node'
+
+    def __repr__(self):
+        return f"Unary({self.op!r}, {self.operand!r})"
+
+
+Node = Union[Num, BinOp, Unary]
+
+
+class _Parser:
+    def __init__(self, tokens: List[Token]):
+        self.tokens = tokens
+        self.pos = 0
+
+    def _peek(self) -> Token:
+        return self.tokens[self.pos]
+
+    def _consume(self, kind: str = None) -> Token:
+        tok = self.tokens[self.pos]
+        if kind and tok.kind != kind:
+            raise ParseError(f"expected {kind!r}, got {tok.kind!r} ({tok.value!r})")
+        self.pos += 1
+        return tok
+
+    def parse(self) -> Node:
+        if self._peek().kind == 'EOF':
+            raise ParseError("empty input")
+        node = self._expr()
+        if self._peek().kind != 'EOF':
+            raise ParseError(
+                f"unexpected token {self._peek().kind!r} ({self._peek().value!r})"
+            )
+        return node
+
+    def _expr(self) -> Node:
+        node = self._term()
+        while self._peek().kind in ('PLUS', 'MINUS'):
+            op = self._consume().value
+            right = self._term()
+            node = BinOp(op, node, right)
+        return node
+
+    def _term(self) -> Node:
+        node = self._unary()
+        while self._peek().kind in ('STAR', 'SLASH'):
+            op = self._consume().value
+            right = self._unary()
+            node = BinOp(op, node, right)
+        return node
+
+    def _unary(self) -> Node:
+        if self._peek().kind == 'MINUS':
+            op = self._consume().value
+            return Unary(op, self._unary())
+        return self._primary()
+
+    def _primary(self) -> Node:
+        tok = self._peek()
+        if tok.kind == 'NUMBER':
+            self._consume()
+            return Num(tok.value)
+        if tok.kind == 'LPAREN':
+            self._consume()
+            node = self._expr()
+            if self._peek().kind != 'RPAREN':
+                raise ParseError(
+                    f"expected ')', got {self._peek().kind!r} ({self._peek().value!r})"
+                )
+            self._consume()
+            return node
+        raise ParseError(f"unexpected token {tok.kind!r} ({tok.value!r})")
+
+
+def parse(tokens: List[Token]) -> Node:
+    """Parse a flat token list into an AST Node.
+
+    AST shape
+    ---------
+    Num(value)              — numeric literal (int or float)
+    BinOp(op, left, right)  — binary op; op in {'+', '-', '*', '/'}
+    Unary(op, operand)      — unary op; op == '-'
+
+    Precedence (high to low): unary-minus > * / > + -
+    Associativity: left for all binary operators.
+
+    Raises ParseError on malformed input.
+    """
+    return _Parser(tokens).parse()