Data commit

Task/Arithmetic-evaluation/11l/arithmetic-evaluation.11l

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+T Symbol
+   String id
+   Int lbp
+   Int nud_bp
+   Int led_bp
+   (ASTNode -> ASTNode) nud
+   ((ASTNode, ASTNode) -> ASTNode) led
+
+   F set_nud_bp(nud_bp, nud)
+      .nud_bp = nud_bp
+      .nud = nud
+
+   F set_led_bp(led_bp, led)
+      .led_bp = led_bp
+      .led = led
+
+T ASTNode
+   Symbol& symbol
+   Int value
+   ASTNode? first_child
+   ASTNode? second_child
+
+   F eval()
+      S .symbol.id
+         ‘(number)’
+            R .value
+         ‘+’
+            R .first_child.eval() + .second_child.eval()
+         ‘-’
+            R I .second_child == N {-.first_child.eval()} E .first_child.eval() - .second_child.eval()
+         ‘*’
+            R .first_child.eval() * .second_child.eval()
+         ‘/’
+            R .first_child.eval() / .second_child.eval()
+         ‘(’
+            R .first_child.eval()
+         E
+            assert(0B)
+            R 0
+
+[String = Symbol] symbol_table
+[String] tokens
+V tokeni = -1
+ASTNode token_node
+
+F advance(sid = ‘’)
+   I sid != ‘’
+      assert(:token_node.symbol.id == sid)
+   :tokeni++
+   :token_node = ASTNode()
+   I :tokeni == :tokens.len
+      :token_node.symbol = :symbol_table[‘(end)’]
+      R
+   V token = :tokens[:tokeni]
+   :token_node.symbol = :symbol_table[I token.is_digit() {‘(number)’} E token]
+   I token.is_digit()
+      :token_node.value = Int(token)
+
+F expression(rbp = 0)
+   ASTNode t = move(:token_node)
+   advance()
+   V left = t.symbol.nud(move(t))
+   L rbp < :token_node.symbol.lbp
+      t = move(:token_node)
+      advance()
+      left = t.symbol.led(t, move(left))
+   R left
+
+F parse(expr_str) -> ASTNode
+   :tokens = re:‘\s*(\d+|.)’.find_strings(expr_str)
+   :tokeni = -1
+   advance()
+   R expression()
+
+F symbol(id, bp = 0) -> &
+   I !(id C :symbol_table)
+      V s = Symbol()
+      s.id = id
+      s.lbp = bp
+      :symbol_table[id] = s
+   R :symbol_table[id]
+
+F infix(id, bp)
+   F led(ASTNode self, ASTNode left)
+      self.first_child = left
+      self.second_child = expression(self.symbol.led_bp)
+      R self
+   symbol(id, bp).set_led_bp(bp, led)
+
+F prefix(id, bp)
+   F nud(ASTNode self)
+      self.first_child = expression(self.symbol.nud_bp)
+      R self
+   symbol(id).set_nud_bp(bp, nud)
+
+infix(‘+’, 1)
+infix(‘-’, 1)
+infix(‘*’, 2)
+infix(‘/’, 2)
+prefix(‘-’, 3)
+
+F nud(ASTNode self)
+   R self
+symbol(‘(number)’).nud = nud
+symbol(‘(end)’)
+
+F nud_parens(ASTNode self)
+   V expr = expression()
+   advance(‘)’)
+   R expr
+symbol(‘(’).nud = nud_parens
+symbol(‘)’)
+
+L(expr_str) [‘-2 / 2 + 4 + 3 * 2’,
+             ‘2 * (3 + (4 * 5 + (6 * 7) * 8) - 9) * 10’]
+   print(expr_str‘ = ’parse(expr_str).eval())