week9

目前已经开始了build a computer系列的最后几章了，后面的章节感觉越来越难，build a computer的part II部分基本上全是软件，需要编码，耗费大量的实践和精力来应付这些代码，不过能够最终通过测试的话还是成就满满。特别是只剩下后面三章了，主要是完成一个jack语言编译器和一个最基本的微型操作系统，并提供基本的系统库函数。project10主要完成jack语言编译器的语法分析，感觉还是非常有难度和挑战的，花了差不多两周时间，利用子集的业余时间终于把蹩脚的语法解析器完成了，主要是关于jack语言的语法分析。收获满满，最终的实现结果是将jack语言的语法分析结果结构化为固定的xml文档，供后面的代码生成器和链接器使用。当然总体来说jack语言的语法还是非常简单的语法，我们直接用常见的top down递归下降分析法即可实现，实际是非常简单的语法，至少感觉总体语法来说比c语言的语法简单多了，非常喜欢这类有挑战性的小project，感觉对基本的递归方法有了更深层次的了解。

• Lexical elements: 词的定义，在jack语言中词的定义非常简单，只有5类基本类型，如下所示：

关键字、符号、整数常数、字符串常数、普通标识符。

• • 关键字即可语法中的关键字，不可随意使用
• • 特殊符号即为过程标志位和运算符
• • 整数常数 (0~32767)
• • 字符串常数 (“xxx”)
• • 普通标识符

• Program structure:结构语法，包含基本的程序结构定义

• Statements：语句定义，还是非常常见的语句定义

• Expressions:表达式定义，包含常见的表达式定义:

整个project基本围绕着上述几个语法展开，实际还是非常有意思的，需要对递归非常熟悉才可以对整个代码比较好的掌握

project

本周的project还是非常有难度的project，刚开始准备用c++来实现，后来发现c++太恶心了点，最后用蹩脚的python花了大概一个星期终于实现了整个project，整个程序的流程也分为两部分，先将整个程序进行token格式化，后续的分析引擎对整个语法树进行分析，生成树状结构的xml文件，当然总的来说本章的project有难度，但是不够有趣，感觉csapp的project难度非常大，不是一般人能够坚持完成的，目前的打算是准备把build a computer这个系列的课程的project代码完整的实现一遍，终于磨蹭了这么长时间只剩下最后两个project了。源代码放在
poj10.

• token parser：整个程序非常简单，其实大概核心的代码100行即可完成token解析，非常简单的代码逻辑即可实现。

  import fileinput import sys, getopt from enum import Enum, unique @unique class TOKEN_TYPE(Enum): TOKEN_KEYWORD = 0 TOKEN_SYMBOL = 1 TOKEN_IDENTIFIER = 2 TOKEN_INT_CONST = 3 TOKEN_STRING_CONST = 4 TOKEN_INVALID = 5 @unique class KEYWORD_TYPE(Enum): KEYWORD_CLASS = 101 KEYWORD_METHOD = 102 KEYWORD_FUNCTION = 103 KEYWORD_CONSTRUCTOR = 104 KEYWORD_BOOLEAN = 105 KEYWORD_CHAR = 106 KEYWORD_VOID = 107 KEYWORD_VAR = 108 KEYWORD_STATIC = 109 KEYWORD_FIELD = 110 KEYWORD_LET = 111 KEYWORD_DO = 112 KEYWORD_IF = 113 KEYWORD_WHILE = 114 KEYWORD_RETURN = 115 KEYWORD_TRUE = 116 KEYWORD_FALSE = 117 KEYWORD_NULL = 118 KEYWORD_THIS = 119 KEYWORD_VALID = 120 keywordname = ["class","method","function","constructor","boolean","char","void","var","static" ,"field","let","do","if","else","while","return","true","false","null","this"] keywordtype = [name for name, member in KEYWORD_TYPE.__members__.items()] keworddict = dict(zip(keywordname,keywordtype)) tokenname = ["keyword","symbol","identifier","integerConstant","stringConstant"] tokentype = [name for name, member in TOKEN_TYPE.__members__.items()] tokendict = dict(zip(tokentype,tokenname)) symboldict = set(['{','}','(',')','[',']',',',';','=','.','+','-','*','/','&','|','~','<','>']) def validNum(val): if len(val) == 0: return False if val[0] == '0' and len(val) > 1: return False for c in val: if ord(c) < ord('0') or ord(c) > ord('9'): return False return True def isAlpha(val): if ord(val) >= ord('a') and ord(val) <= ord('z'): return True if ord(val) >= ord('A') and ord(val) <= ord('Z'): return True return False def isDigit(val): if ord(val) >= ord('0') and ord(val) <= ord('9'): return True return False def validIdentifiers(val): if not (val[0] == '_' or isAlpha(val[0])): return False for i in range(1,len(val)): if not (val[i] == '_' or isAlpha(val[i]) or isDigit(val[i])): return False return True class JackTokenizer: def __init__(self,infile): # read all source code string to the buffer self.curr = 0 self.buffer = "" with open(infile,"r") as ifs: self.buffer = ifs.read() ifs.close() self.end = len(self.buffer) self.tokens = [] self.linenum = [] self.parseToken() self.outfile = infile[:infile.find(".jack")] + "T.xml" self.genToken() def parseToken(self): pos = 0 while pos < self.end: #we will skip space if self.buffer[pos] == ' ' or \ self.buffer[pos] == '\n' or \ self.buffer[pos] == '\t': while pos < self.end and (self.buffer[pos] == ' ' or \ self.buffer[pos] == '\n' or \ self.buffer[pos] == '\t'): pos += 1 continue # we will skip the comment "//" if self.buffer[pos:pos+2] == "//": while pos < self.end and self.buffer[pos] != '\n': pos += 1 continue # we will skip the comment "/* .. */" if self.buffer[pos:pos+2] == "/*": while pos < self.end and self.buffer[pos:pos+2] != "*/": pos += 1 pos += 2 continue # check curr token is symbol if self.buffer[pos] in symboldict: self.tokens.append(self.buffer[pos:pos+1]) pos += 1 continue # check string constant if pos < self.end and self.buffer[pos] == '"': posCurr = pos pos += 1 while pos < self.end and self.buffer[pos] != '"': pos += 1 pos += 1 self.tokens.append(self.buffer[posCurr:pos]) continue # check curr token posCurr = pos while pos < self.end and self.buffer[pos] != ' ' and \ self.buffer[pos] != '\n' and self.buffer[pos] not in symboldict: pos += 1 if pos > posCurr: self.tokens.append(self.buffer[posCurr:pos]) return True def hasMoreTokens(self): if self.curr >= len(self.tokens) - 1: return False return True def advance(self): self.curr += 1 def currToken(self): return self.tokens[self.curr] def tokenType(self): return self.getType(self.tokens[self.curr]) def getType(self,token): if token in keworddict: return TOKEN_TYPE.TOKEN_KEYWORD elif len(token) == 1 and token[0] in symboldict: return TOKEN_TYPE.TOKEN_SYMBOL elif validNum(token): return TOKEN_TYPE.TOKEN_INT_CONST elif len(token) > 1 and token[0] == '"' and token[-1] == '"': return TOKEN_TYPE.TOKEN_STRING_CONST elif validIdentifiers(token): return TOKEN_TYPE.TOKEN_IDENTIFIER else: return TOKEN_TYPE.TOKEN_INVALID def keyWord(self): return self.tokens[self.curr] def symbol(self): return self.tokens[self.curr] def identifier(self): return self.tokens[self.curr] def intVal(self): return self.tokens[self.curr] def stringVal(self): return self.tokens[self.curr][1:-1] def genToken(self): out = open(self.outfile,"w") out.write("<tokens>\n") for token in self.tokens: t = self.getType(token) if t == TOKEN_TYPE.TOKEN_KEYWORD: out.write("<keyword> ") out.write(token) out.write(" </keyword>\n") elif t == TOKEN_TYPE.TOKEN_SYMBOL: out.write("<symbol> ") out.write(token) out.write(" </symbol>\n") elif t == TOKEN_TYPE.TOKEN_INT_CONST: out.write("<integerConstant> ") out.write(token) out.write(" </integerConstant>\n") elif t == TOKEN_TYPE.TOKEN_STRING_CONST: out.write("<stringConstant> ") out.write(token[1:-1]) out.write(" </stringConstant>\n") elif t == TOKEN_TYPE.TOKEN_IDENTIFIER: out.write("<identifier> ") out.write(token) out.write(" </identifier>\n") out.write("</tokens>\n") out.close() def main(input): parser = JackTokenizer(input) parser.genToken() if __name__ == "__main__": main(sys.argv[1])

• compile engine：整个的语法解析器还是非常复杂的，但是实际实现的project可以根据配套的《The Elements of Computing Systems》中的提示，可以很快的将代码解析为几个关键函数的实现即可。

  from JackTokenizer import JackTokenizer,TOKEN_TYPE,KEYWORD_TYPE,tokentype,tokendict import fileinput import sys, getopt from enum import Enum, unique import sys class CompilationEngine: def __init__(self,infile): # read all source code string to the buffer self.parser = JackTokenizer(infile) outfile = infile[:infile.find(".jack")] + ".xml" self.out = open(outfile,"w") self.depth = 0 self.compileClass() self.out.close() def lowerLevel(self): self.depth += 1 def upperLevel(self): self.depth -= 1 def compileOut(self,str): self.out.write(" "*self.depth) self.out.write(str) def compileOutElement(self,tkType,tkStr): self.out.write(" "*self.depth) typeStr = "" if tkType == TOKEN_TYPE.TOKEN_KEYWORD: typeStr = "keyword" elif tkType == TOKEN_TYPE.TOKEN_SYMBOL: typeStr = "symbol" elif tkType == TOKEN_TYPE.TOKEN_IDENTIFIER: typeStr = "identifier" elif tkType == TOKEN_TYPE.TOKEN_INT_CONST: typeStr = "integerConstant" elif tkType == TOKEN_TYPE.TOKEN_STRING_CONST: typeStr = "stringConstant" elif tkType == TOKEN_TYPE.TOKEN_INVALID: typeStr = "invalid" self.out.write("<" + typeStr + "> " + tkStr + " </" + typeStr + ">\n") def compileClass(self): self.compileOut("<class>\n") self.lowerLevel() # parse class if self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD and \ self.parser.keyWord() == "class": self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print(str(sys._getframe().f_lineno) + "valid class define!\n") exit(1) # parse class name if self.parser.tokenType() == TOKEN_TYPE.TOKEN_IDENTIFIER: self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print(str(sys._getframe().f_lineno) + "valid class define!\n") exit(1) # parse symbol '{' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == "{": self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print(str(sys._getframe().f_lineno) + "valid class define!\n") exit(1) #parse class val des while self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD and \ (self.parser.keyWord() == "static" or self.parser.keyWord() == "field"): self.compileClassVarDec() #parse class method while self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD and \ (self.parser.keyWord() == "method" or \ self.parser.keyWord() == "constructor" or \ self.parser.keyWord() == "function"): self.compileSubroutine() #parse symbol '{' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == "}": self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print(str(sys._getframe().f_lineno) + "valid class define!\n") exit(1) # end of parse class self.upperLevel() self.compileOut("</class>\n") return True def compileClassVarDec(self): self.compileOut("<classVarDec>\n") self.lowerLevel() # parse key word if self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD and \ (self.parser.keyWord() == "static" or self.parser.keyWord() == "field"): self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print(str(sys._getframe().f_lineno) + "valid val define!\n") exit(1) # parse val type if self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD or \ self.parser.tokenType() == TOKEN_TYPE.TOKEN_IDENTIFIER: self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print(str(sys._getframe().f_lineno) + "valid val define!\n") exit(1) # parse val name if self.parser.tokenType() == TOKEN_TYPE.TOKEN_IDENTIFIER: self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print(str(sys._getframe().f_lineno) + "valid val define!\n") exit(1) # parse the left val name while not (self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == ";"): # parse symbol ',' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and self.parser.symbol() == ",": self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print(str(sys._getframe().f_lineno) + "valid val define!\n") exit(1) # parse val name if self.parser.tokenType() == TOKEN_TYPE.TOKEN_IDENTIFIER: self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print(str(sys._getframe().f_lineno) + "valid val define!\n") exit(1) # parse the end symbol if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and self.parser.symbol() == ";": self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print(str(sys._getframe().f_lineno) + "valid val define!\n") exit(1) # end of class var descrtion self.upperLevel() self.compileOut("</classVarDec>\n") return True def compileSubroutine(self): self.compileOut("<subroutineDec>\n") self.lowerLevel() # parse key word if self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD and \ (self.parser.keyWord() == "constructor" or \ self.parser.keyWord() == "function" or \ self.parser.keyWord() == "method"): self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print(str(sys._getframe().f_lineno) + "invalid subroutine!\n") exit(1) # parse type if (self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD and \ (self.parser.keyWord() == "int" or \ self.parser.keyWord() == "char" or \ self.parser.keyWord() == "void" or \ self.parser.keyWord() == "boolean")) or \ self.parser.tokenType() == TOKEN_TYPE.TOKEN_IDENTIFIER: if self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD: self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() elif self.parser.tokenType() == TOKEN_TYPE.TOKEN_IDENTIFIER: self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print(str(sys._getframe().f_lineno) + "invalid subroutine!\n") exit(1) # parse subroutineName if self.parser.tokenType() == TOKEN_TYPE.TOKEN_IDENTIFIER: self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print(str(sys._getframe().f_lineno) + "invalid subroutine!\n") exit(1) # parse '(' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and self.parser.symbol() == "(": self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print(str(sys._getframe().f_lineno) + "invalid subroutine!\n") exit(1) # parse param list self.compileParameterList() # parse ')' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and self.parser.symbol() == ")": self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print(str(sys._getframe().f_lineno) + "invalid subroutine!\n") exit(1) # parse body self.compileSubroutineBody() self.upperLevel() self.compileOut("</subroutineDec>\n") return True def compileSubroutineBody(self): self.compileOut("<subroutineBody>\n") self.lowerLevel() # parse '{' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == "{": self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print("inValid sub routine body define!\n") exit(1) # parse var while self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD and \ self.parser.keyWord() == "var": self.compileVarDec() # parse statements self.compileStatements() # parse '}' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == "}": self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("inValid sub routine body define!\n") exit(1) self.upperLevel() self.compileOut("</subroutineBody>\n") return True def compileParameterList(self): self.compileOut("<parameterList>\n") self.lowerLevel() # parse rest param while not (self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and\ self.parser.symbol() == ")"): # parse first element type if self.parser.tokenType() == TOKEN_TYPE.TOKEN_IDENTIFIER or \ (self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD and \ (self.parser.keyWord() == "int" or self.parser.keyWord() == "char" or \ self.parser.keyWord() == "boolean")): self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() # parse first element varName if self.parser.tokenType() == TOKEN_TYPE.TOKEN_IDENTIFIER: self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() # parse ',' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL: if self.parser.symbol() == ",": self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() elif self.parser.symbol() == ")": break else: print(str(sys._getframe().f_lineno) + "valid param list!\n") exit(1) else: print(str(sys._getframe().f_lineno) + "valid param list!\n") exit(1) self.upperLevel() self.compileOut("</parameterList>\n") return True def compileVarDec(self): self.compileOut("<varDec>\n") self.lowerLevel() # parse key word if self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD and \ self.parser.keyWord() == "var": self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print("valid val define!\n") exit(1) # parse var type if self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD or \ self.parser.tokenType() == TOKEN_TYPE.TOKEN_IDENTIFIER: self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print("valid val define!\n") exit(1) # parse var name if self.parser.tokenType() == TOKEN_TYPE.TOKEN_IDENTIFIER: self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print("valid val define!\n") exit(1) # parse the rest var name while not (self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == ";"): # parse "," if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and self.parser.symbol() == ",": self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print("valid val define!\n") exit(1) # parse var name if self.parser.tokenType() == TOKEN_TYPE.TOKEN_IDENTIFIER: self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print("valid val define!\n") exit(1) # parse the end symbol if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == ";": self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print("valid var define!\n") exit(1) # end of class var descrtion self.upperLevel() self.compileOut("</varDec>\n") return True def compileStatements(self): self.compileOut("<statements>\n") self.lowerLevel() while self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD and \ (self.parser.keyWord() == "do" or \ self.parser.keyWord() == "if" or \ self.parser.keyWord() == "while" or \ self.parser.keyWord() == "let" or \ self.parser.keyWord() == "return"): if self.parser.keyWord() == "do": self.compileDo() elif self.parser.keyWord() == "if": self.compileIf() elif self.parser.keyWord() == "while": self.compileWhile() elif self.parser.keyWord() == "let": self.compileLet() elif self.parser.keyWord() == "return": self.compileReturn() else: print("valid statement define!\n") exit(1) self.upperLevel() self.compileOut("</statements>\n") return True def compileDo(self): self.compileOut("<doStatement>\n") self.lowerLevel() # parse do if self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD and \ self.parser.keyWord() == "do": self.compileOutElement(self.parser.tokenType(),self.parser.keyWord()) self.parser.advance() else: print("inValid do define!\n") exit(1) # parse '(' while not (self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == "("): self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() # parse '(' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == "(": self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("inValid do statement define!\n") exit(1) # parse expression list self.compileExpressionList() # parse ')' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == ")": self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("inValid do statement body define!\n") exit(1) # parse ';' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == ';': self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("inValid do statement define!\n") exit(1) self.upperLevel() self.compileOut("</doStatement>\n") return True def compileLet(self): self.compileOut("<letStatement>\n") self.lowerLevel() # parse let if self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD and \ self.parser.keyWord() == "let": self.compileOutElement(self.parser.tokenType(),self.parser.keyWord()) self.parser.advance() else: print("inValid let define!\n") exit(1) # parse varname if self.parser.tokenType() == TOKEN_TYPE.TOKEN_IDENTIFIER: self.compileOutElement(self.parser.tokenType(),self.parser.identifier()) self.parser.advance() else: print("inValid let define!\n") exit(1) # parse `[expression]` while self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == '[': # parse '[' self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() # parse expression self.compileExpression() # parse ']' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == ']': self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("inValid let define!\n") exit(1) # parse '=' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == '=': self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("inValid let define!\n") exit(1) # parse expression self.compileExpression() # parse ';' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == ';': self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("inValid let define!\n") exit(1) self.upperLevel() self.compileOut("</letStatement>\n") return True def compileWhile(self): self.compileOut("<whileStatement>\n") self.lowerLevel() # parse return if self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD and \ self.parser.keyWord() == "while": self.compileOutElement(self.parser.tokenType(),self.parser.keyWord()) self.parser.advance() else: print("inValid while define!\n") exit(1) # parse '(' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == '(': self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("inValid while define!\n") exit(1) # parse expression self.compileExpression() # parse ')' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == ')': self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("inValid while define!\n") exit(1) # parse '{' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == '{': self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("inValid while define!\n") exit(1) # parse statements self.compileStatements() # parse '}' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == '}': self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("inValid while define!\n") exit(1) self.upperLevel() self.compileOut("</whileStatement>\n") return True def compileReturn(self): self.compileOut("<returnStatement>\n") self.lowerLevel() # parse return if self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD and \ self.parser.keyWord() == "return": self.compileOutElement(self.parser.tokenType(),self.parser.keyWord()) self.parser.advance() else: print("valid if return statement!\n") exit(1) # parse expression list if not (self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == ';'): self.compileExpression() # parse ';' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == ';': self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("valid if return statement!\n") exit(1) self.upperLevel() self.compileOut("</returnStatement>\n") return True def compileIf(self): self.compileOut("<ifStatement>\n") self.lowerLevel() # parse if if self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD and \ self.parser.keyWord() == "if": self.compileOutElement(self.parser.tokenType(),self.parser.keyWord()) self.parser.advance() else: print("valid if define!\n") exit(1) # parse '(' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == "(": self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("valid if define!\n") exit(1) # parse expression self.compileExpression() # parse ')' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == ")": self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("valid if define!\n") exit(1) # parse '{' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == "{": self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("valid if define!\n") exit(1) # parse statements self.compileStatements() # parse '}' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == "}": self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("valid if define!\n") exit(1) # parse else if self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD and \ self.parser.keyWord() == "else": # parse 'else' self.compileOutElement(self.parser.tokenType(),self.parser.keyWord()) self.parser.advance() # parse '{' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == "{": self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("valid if define!\n") exit(1) # parse statements self.compileStatements() # parse '}' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == "}": self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("valid if define!\n") exit(1) self.upperLevel() self.compileOut("</ifStatement>\n") return def compileExpression(self): self.compileOut("<expression>\n") self.lowerLevel() # parse term self.compileTerm() # parse op while self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ (self.parser.symbol() == "+" or self.parser.symbol() == "-" or \ self.parser.symbol() == "*" or self.parser.symbol() == "/" or \ self.parser.symbol() == "&" or self.parser.symbol() == "|" or \ self.parser.symbol() == ">" or self.parser.symbol() == "<" or \ self.parser.symbol() == "="): # parse op self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() # parse term self.compileTerm() self.upperLevel() self.compileOut("</expression>\n") return def compileTerm(self): self.compileOut("<term>\n") self.lowerLevel() if self.parser.tokenType() == TOKEN_TYPE.TOKEN_INT_CONST: # parse int const self.compileOutElement(self.parser.tokenType(),self.parser.intVal()) self.parser.advance() elif self.parser.tokenType() == TOKEN_TYPE.TOKEN_STRING_CONST: # parse string const self.compileOutElement(self.parser.tokenType(),self.parser.stringVal()) self.parser.advance() elif self.parser.tokenType() == TOKEN_TYPE.TOKEN_KEYWORD: # parse keword const if self.parser.keyWord() == "true" or self.parser.keyWord() == "false" or \ self.parser.keyWord() == "null" or self.parser.keyWord() == "this": self.compileOutElement(self.parser.tokenType(),self.parser.keyWord()) self.parser.advance() else: print("inValid expression define!\n") exit(1) elif self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL: if self.parser.symbol() == "(": # parse '(' self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() # parse expression self.compileExpression() # parse ')' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ self.parser.symbol() == ")": self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("valid term define!\n") exit(1) elif self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and \ (self.parser.symbol() == "-" or self.parser.symbol() == "~"): # parse unaryOp self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() # parse term self.compileTerm() else: print("valid term define!\n") exit(1) elif self.parser.tokenType() == TOKEN_TYPE.TOKEN_IDENTIFIER: # parse subroutineName or varName self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() # parse expression if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and self.parser.symbol() == "[": # parse '[' self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() # parse expression self.compileExpression() # parse ']' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and self.parser.symbol() == "]": self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("valid term define!\n") exit(1) elif self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and self.parser.symbol() == ".": # parse '.' self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() # parse subroutineName if self.parser.tokenType() == TOKEN_TYPE.TOKEN_IDENTIFIER: self.compileOutElement(self.parser.tokenType(),self.parser.currToken()) self.parser.advance() else: print("valid term define!\n") exit(1) # parse '(' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and self.parser.symbol() == "(": self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("valid term define!\n") exit(1) # parse expressList self.compileExpressionList() # parse ')' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and self.parser.symbol() == ")": self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("valid term define!\n") exit(1) elif self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and self.parser.symbol() == "(": self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() # parse expressList self.compileExpressionList() # parse ')' if self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL and self.parser.symbol() == ")": self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() else: print("valid term define!\n") exit(1) self.upperLevel() self.compileOut("</term>\n") return True def compileExpressionList(self): self.compileOut("<expressionList>\n") self.lowerLevel() if self.parser.symbol() == ')' and \ self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL: self.upperLevel() self.compileOut("</expressionList>\n") return True # parse expression self.compileExpression() # parse `, expression` while self.parser.symbol() == ',' and \ self.parser.tokenType() == TOKEN_TYPE.TOKEN_SYMBOL: # parse ',' self.compileOutElement(self.parser.tokenType(),self.parser.symbol()) self.parser.advance() # parse expression self.compileExpression() self.upperLevel() self.compileOut("</expressionList>\n") return def main(input): parser = CompilationEngine(input) if __name__ == "__main__": main(sys.argv[1])

欢迎关注和打赏，感谢支持！

• 关注我的博客: http://mikemeng.org/
• 关注我的知乎：https://www.zhihu.com/people/da-hua-niu
• 关注我的微信公众号: 公务程序猿