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