def printStmt():
expr = Expr(ExprType.PRINT)
expr.token = nextToken()
expr.eval = evalPrint
expr.right = expression()
consume(TokenType.SEMICOLON)
return expr
def returnStmt():
expr = Expr(ExprType.RETURN, nextToken())
expr.eval = evalReturn
if not matchesToken(TokenType.SEMICOLON):
expr.right = expr.right = expression()
consume(TokenType.SEMICOLON)
return expr
def unary():
if matchesToken(TokenType.BANG, TokenType.MINUS):
expr = Expr(ExprType.UNARY, nextToken())
expr.eval = evalUnary
expr.right = unary()
return expr
else:
return call()
def primary():
result = Expr()
if matchesToken(TokenType.LEFT_PAREN):
result.type = ExprType.GROUPING
result.token = nextToken()
result.right = addition()
result.eval = evalGrouping
if not matchesToken(TokenType.RIGHT_PAREN):
raise ParseException(
"Expecting ')', found {0}".format(peekToken().text),
peekToken())
else:
nextToken()
elif matchesToken(TokenType.IDENTIFIER):
result.type = ExprType.IDENTIFIER
result.eval = evalVariableGet
result.token = nextToken()
else:
result.type = ExprType.LITERAL
result.eval = evalLiteral
result.token = peekToken()
if matchesToken(TokenType.FALSE):
result.value = False
result.dataType = DataType.BOOLEAN
elif matchesToken(TokenType.TRUE):
result.value = True
result.dataType = DataType.BOOLEAN
elif matchesToken(TokenType.NIL):
result.value = None
result.dataType = DataType.NIL
elif matchesToken(TokenType.STRING):
result.value = result.token.text
result.dataType = DataType.STRING
elif matchesToken(TokenType.NUMBER):
if result.token.text.find(".") > -1:
result.value = float(result.token.text)
result.dataType = DataType.DOUBLE
else:
result.value = int(result.token.text)
result.dataType = DataType.INTEGER
nextToken()
return result
def assignment():
expr = logicOr()
if matchesToken(TokenType.EQUAL):
assExpr = Expr(ExprType.ASSIGNMENT, nextToken())
assExpr.eval = evalAssignment
assExpr.left = expr
assExpr.right = assignment()
expr = assExpr
return expr
def block():
expr = Expr(ExprType.BLOCK, nextToken())
expr.eval = evalBlock
statements = list()
while not matchesToken(TokenType.RIGHT_BRACE) and not isEndOfTokens():
statements.append(declaration())
consume(TokenType.RIGHT_BRACE)
expr.right = statements
return expr
def ifStmt():
expr = Expr(ExprType.IF, nextToken())
expr.eval = evalIf
consume(TokenType.LEFT_PAREN)
expr.condition = expression()
consume(TokenType.RIGHT_PAREN)
expr.left = statement()
if matchesToken(TokenType.ELSE):
consume(TokenType.ELSE)
expr.right = statement()
return expr
def equality():
expr = comparison()
while matchesToken(TokenType.BANG_EQUAL, TokenType.EQUAL_EQUAL):
leftExpr = expr
expr = Expr(ExprType.BINARY, nextToken())
expr.eval = evalEquality
expr.left = leftExpr
expr.right = comparison()
return expr
def funDecl():
expr = Expr(ExprType.FUNCTION, nextToken())
if not matchesToken(TokenType.IDENTIFIER):
raise ParseException(
"Expected fucntion identifier, found {0}".format(peekToken().text),
peekToken())
expr.value = consume(TokenType.IDENTIFIER).text
expr.left = parameters()
expr.right = block()
expr.eval = evalFunc
return expr
def multiplication():
expr = unary()
while matchesToken(TokenType.SLASH, TokenType.STAR):
leftExpr = expr
expr = Expr(ExprType.BINARY, nextToken())
expr.eval = evalMultiplication
expr.left = leftExpr
expr.right = unary()
return expr
def call():
expr = primary()
if matchesToken(TokenType.LEFT_PAREN):
callExpr = Expr(ExprType.CALL, nextToken())
callExpr.left = expr
callExpr.right = arguments()
callExpr.eval = evalCall
consume(TokenType.RIGHT_PAREN)
expr = callExpr
return expr
def addition():
expr = multiplication()
while matchesToken(TokenType.PLUS, TokenType.MINUS):
leftExpr = expr
expr = Expr(ExprType.BINARY, nextToken())
expr.eval = evalAddition
expr.left = leftExpr
expr.right = multiplication()
return expr
def comparison():
expr = addition()
while matchesToken(TokenType.GREATER, TokenType.GREATER_EQUAL,
TokenType.LESS, TokenType.LESS_EQUAL):
leftExpr = expr
expr = Expr(ExprType.BINARY, nextToken())
expr.eval = evalComparison
expr.left = leftExpr
expr.right = addition()
return expr
def whileStmt():
token = nextToken()
consume(TokenType.LEFT_PAREN)
conditional = expression()
consume(TokenType.RIGHT_PAREN)
body = statement()
expr = Expr(ExprType.WHILE, token)
expr.condition = conditional
expr.right = body
expr.eval = evalWhile
return expr
def logicAnd():
expr = equality()
while matchesToken(TokenType.AND):
token = nextToken()
right = equality()
left = expr
expr = Expr(ExprType.AND, token)
expr.left = left
expr.right = right
expr.eval = evalLogical
return expr
def logicOr():
expr = logicAnd()
while matchesToken(TokenType.OR):
token = nextToken()
right = logicAnd()
left = expr
expr = Expr(ExprType.OR, token)
expr.left = left
expr.right = right
expr.eval = evalLogical
return expr
def varDecl():
expr = Expr(ExprType.VAR, nextToken())
if matchesToken(TokenType.IDENTIFIER):
expr.left = Expr(ExprType.IDENTIFIER, nextToken())
expr.eval = evalVariableDecl
else:
raise ParseException(
"Identifier expected, found {0}".format(peekToken()[1]), 0)
if matchesToken(TokenType.EQUAL):
nextToken()
expr.right = expression()
consume(TokenType.SEMICOLON)
return expr
def forStmt():
expr = Expr(ExprType.FOR, nextToken())
consume(TokenType.LEFT_PAREN)
if matchesToken(TokenType.VAR):
expr.left = varDecl()
elif not matchesToken(TokenType.SEMICOLON):
expr.left = exprStmt()
else:
consume(TokenType.SEMICOLON)
if not matchesToken(TokenType.SEMICOLON):
expr.condition = expression()
consume(TokenType.SEMICOLON)
if not matchesToken(TokenType.RIGHT_PAREN):
expr.increment = expression()
consume(TokenType.RIGHT_PAREN)
expr.right = statement()
expr.eval = evalFor
return expr
def expression():
expr = Expr()
expr.eval = evalExpr
return assignment()