mirror of
https://github.com/Ed94/LangStudies.git
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180 lines
3.7 KiB
GDScript
180 lines
3.7 KiB
GDScript
extends Object
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# ---------------------------------------------------------- UTILITIES
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var EvalOut
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func check( condition : bool, message : String):
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assert(condition, message)
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if ! condition:
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EvalOut.text = "Eva - Error: " + message
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func throw( message ):
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assert(false, message)
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EvalOut.text = "Eva - Error: " + message
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# ---------------------------------------------------------- UTILITIES END
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class_name Eva
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# ---------------------------------------------------------- GLOBALS
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const Parser = preload("Parser.gd")
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const NType = Parser.NType
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const EvaEnv = preload("EvaEnv.gd")
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var Env : EvaEnv
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var Parent
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# ---------------------------------------------------------- GLOBALS END
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func _init(parent, evalOut):
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EvalOut = evalOut
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Env = EvaEnv.new(EvalOut)
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Parent = parent
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func eval( ast ):
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match ast.type():
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NType.program :
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var index = 1;
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while index < ast.num_args():
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eval( ast.arg(index) )
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index += 1
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var result = eval( ast.arg(index) )
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if result != null:
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return String( result )
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else:
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return null
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NType.block :
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return eval_Block( ast )
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NType.conditional:
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var condition = eval( ast.arg(1) )
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if condition:
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# consequent
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return eval( ast.arg(2) )
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# Alternate
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if ast.num_args() > 2:
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return eval( ast.arg(3))
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NType.expr_While:
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var result
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while eval( ast.arg(1) ):
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result = eval( ast.arg(2) )
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return result
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NType.identifier :
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var identifier = ast.arg(1)
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if Parent != null && !Env.has( identifier):
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return Parent.Env.lookup( identifier )
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return Env.lookup( identifier )
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NType.op_Assign :
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var symbol = ast.arg(1)
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var value = eval( ast.arg(2) )
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if Parent != null && !Env.has( symbol):
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return Parent.Env.set( symbol, value )
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return Env.set( symbol, value )
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NType.op_Greater:
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return eval( ast.arg(1) ) > eval( ast.arg(2) )
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NType.op_Lesser:
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return eval( ast.arg(1) ) < eval( ast.arg(2) )
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NType.op_GreaterEqual:
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return eval( ast.arg(1) ) >= eval( ast.arg(2) )
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NType.op_LesserEqual:
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return eval( ast.arg(1) ) <= eval( ast.arg(2) )
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NType.fn_Print :
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return eval_Print( ast )
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NType.variable :
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var symbol = ast.arg(1)
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var value = eval( ast.arg(2) )
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Env.define_Var(symbol, value)
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return value
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if ast.is_Number() :
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return float( ast.arg(1) )
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elif ast.is_String() :
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return ast.string()
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return eval_Numeric( ast )
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func eval_Block( ast ):
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var eva_Block = get_script().new( self, EvalOut )
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var result
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var index = 1;
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while index <= ast.num_args() :
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result = eva_Block.eval( ast.arg(index) )
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index += 1
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return result
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func eval_Numeric( ast ):
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if ast.type() == NType.op_Add:
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var result = 0.0; var index = 1
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while index <= ast.num_args():
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result += eval( ast.arg(index) )
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index += 1
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return result
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if ast.type() == NType.op_Sub:
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var result = 0.0; var index = 1
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while index <= ast.num_args():
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result -= eval( ast.arg(index) )
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index += 1
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return result
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if ast.type() == NType.op_Mult:
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var result = 1.0; var index = 1
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while index <= ast.num_args():
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result *= eval( ast.arg(index) )
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index += 1
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return result
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if ast.type() == NType.op_Div:
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var result = 1.0; var index = 1
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while index <= ast.num_args():
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result /= eval( ast.arg(index) )
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result += 1
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return result
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var msgT = "eval - Unimplemented: {ast}"
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var msg = msgT.format({"ast" : JSON.print(ast.to_SExpression(), "\t") })
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throw(msg)
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func eval_Print( ast ):
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EvalOut.text += "\n" + String( eval( ast.arg(1) ) )
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return null
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func get_EnvSnapshot():
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var snapshot = Env.Records.duplicate(true)
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if Parent != null:
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snapshot[Parent] = Parent.Env.Records.duplicate(true)
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return snapshot
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