finish calucator

minlisp.rb

@@ -2,6 +2,17 @@
 # Author: @vonhyou
 # Start at: Apr. 10, 2021
 
+##### Parser
+# :parse
+# :tokenize
+# :read_tokens
+# :atom
+#####
+
+def parse(program)
+  read_tokens(tokenize(program))
+end
+
 def tokenize(program)
   # Convert scripts to token lists
   replacements = { '(' => ' ( ', ')' => ' ) ' }
@@ -9,30 +20,90 @@ def tokenize(program)
          .split(' ')
 end
 
+def make_list(tokens)
+  lst = []
+  lst << read_tokens(tokens) while tokens[0] != ')'
+  tokens.shift
+  lst
+end
+
 def read_tokens(tokens)
   # read expressions from token
   raise SyntaxError, 'Unexpected EOF' if tokens.empty?
 
   token = tokens.shift
-  if token == '('
-    lst = []
-    lst << read_tokens(tokens) while tokens[0] != ')'
-    tokens.shift
-    return lst
-  elsif token == ')'
+  case token
+  when '('
+    make_list tokens
+  when ')'
     raise SyntaxError, "Unexpected ')'"
   else
-    return atom token
+    atom token
   end
 end
 
-def isInteger?(atom) = atom.match?(/^-?\d+$/)
-def isFloat?(atom)   = atom.match?(/^(-?\d+)(\.\d+)?$/)
-
 def atom(token)
   # Analyse numbers and symbols
-  return Integer token if isInteger? token
-  return Float   token if isFloat?   token
-  token
+  isInteger = ->(atom) { atom.match?(/^-?\d+$/) }
+  isFloat   = ->(atom) { atom.match?(/^(-?\d+)(\.\d+)?$/) }
+  return Integer token if isInteger.call token
+  return Float   token if isFloat.call   token
+
+  token.to_sym
 end
 
+# p parse '(def 1 2 (c 3.3 (r f r) e))'
+
+
+##### Environments
+
+def generate_env
+  lisp_env = {
+    '+': ->(arr) { arr.sum }, # args.inject(0, :+)
+    '-': ->(*args) { eval args.join('-') },
+    '*': ->(*args) { eval args.join('*') },
+    '/': ->(*args) { eval args.join('/') },
+    '>': ->(x, y) { x > y },
+    '<': ->(x, y) { x < y },
+    '=': ->(x, y) { x == y },
+    '>=': ->(x, y) { x >= y },
+    '<=': ->(x, y) { x <= y },
+    'min': ->(*args) { args.min },
+    'max': ->(*args) { args.max },
+    'car': ->(arr) { arr[0] },
+    'cdr': ->(arr) { arr[1..-1] }
+  }
+end
+
+# puts lisp_env[:+].call 1, 2, 3
+# puts lisp_env[:-].call 1, 2, 3
+# puts lisp_env[:*].call 2, 3, 4
+# puts lisp_env[:/].call 9, 5, 1
+# puts lisp_env[:>].call 1, 2
+
+# p lisp_env[:car].call [1, 2, 3]
+# p lisp_env[:cdr].call [1, 2, 3]
+
+def do_sth ; end
+
+##### Lisp Eval
+
+def lisp_eval(elem, env = generate_env)
+  if elem.instance_of?(Symbol)
+    env[elem]
+  elsif elem.instance_of?(Integer) || elem.instance_of?(Float)
+    elem
+  elsif elem[0] == :def
+    do_sth
+  elsif elem[0] == :if
+    do_sth
+  else
+    args = []
+    elem[1..-1].each { |arg| args << lisp_eval(arg, env) }
+    p lisp_eval(elem[0], env)
+    lisp_eval(elem[0], env).call args
+  end
+end
+
+
+p lisp_eval(parse '(/ (+ 1 (* 2 3) 1 1 (+ 1 (- 7 2) 1)) 4)')