python 中间代码生成器的设计 编译原理
目录
本文内容：
实验过程：
1.转为LL(1)文法：
2.根据LL(1)文法写出递归下降子程序：
3.根据语义，修改递归子程序，使其能生成中间代码
输入示例：
输出示例：
本文内容：
给出以下文法，写出其能生成三地址码的中间代码生成器：
S->id=E;
S->if C then S;
S->while C do S;
C->E>E;
C->EE=E;
E->E+T;
E->E-T;
E->T;
T->T*F;
T->T/F;
T->F;
F->(E);
F->id;
F->int;
1、考虑给定的文法，消除左递归，提取左因子。
2、编制并化简语法图
3、编制递归子程序的算法4、编制各个递归子程序函数
5、连接实验一的词法分析函数scan( )，进行测试6、设计三地址代码生成的数据结构和算法
7、将各个递归子程序函数改写为代码生成函数8、编制测试程序(main函数）
9、调试程序:输入一个语句，检查输出的三地址代码
实验过程：
1.转为LL(1)文法：
使用python 预备实验2 LL(1)文法构造里的方法，将给出的文法转为LL(1)文法
注意，由于该文章方法将每一个独立的字符看成非终结符，所以需要对文法做出更改，之后再变回来：
id = o f = if t = then w = while d = do 1 = int
S->o=E;
S->f C t S;
S->w C d S;
C->E>E;
C->EE=E;
E->E+T;
E->E-T;
E->T;
T->T*F;
T->T/F;
T->F;
F->(E);
F->o;
F->1; 消除左递归并转化回来的文法如下：
后面两列分别是首符集和后继符集。
# 经过处理后的文法如下:
# S->id=E|if C then S|while C do S; id if while ;
# C->EC'; ( id int then do
# E->TE'; ( id int > = < ) ; then do
# T->FT'; ( id int + - > = < ) ; then do
# F->(E)|id|int; ( id int * / + - > = < ) ; then do
# E'->+TE'|-TE'|; + - e > = < ) ; then do
# T'->*FT'|/FT'|; * / e + - > = < ) ; then do
# C'->>E|=E| = < then do 2.根据LL(1)文法写出递归下降子程序：
子程序写法看这：python 递归下降分析法的设计与实验原理 编译原理
注意，这里的scan()为了能适配16进制和8进制做了一点改变，关键字里也有添加
# scan 部分=============================================================================
# =====================================================================================
# 输出结果
def output(str, a, b, type):
global program
program.append([type, str[a:b + 1]])
# 判断字符串一部分是否属于关键字
# 是返回1不是返回2
def iskeywords(str, a, b):
# 关键字
keywords = {"if", "int", "for", "while", "do", "return", "break", "continue", 'then'}
s = str[a:b] # 拷贝字符
if s in keywords: # 判断是否存在，存在返回1，否则返回2
return 1
else:
return 2
# 判断字符是否属于运算符或分隔符的一部分。
# 不是返回0，是返回1，是且后面能跟=号返回2
def belong_to(str, type):
if type == 4: # 选择运算符
library = "+-*/=>= 4:
return 2
else:
return 1
return 0
# 递归的词法分析函数，读入一行str字符串，初始位置 n = 0
# 分离+判断，打印输出类型
# 由之前的c语言版本改写而成
def scan(str, n):
# 7 种类型(最后输出1 - 5)
# -1
# 0: 初始
# 1: 关键字, 在keywords中
# 2: 标识符
# 3: 常数(无符号整型)
# 4: 运算符和界符:+ - * / = > < >= <= !=
# 5: 分隔符:, ; {}()
# 6: 特殊数字（0x64 或者0o77（16进制或者8进制））开始判断
# 7：特殊数字（0xa（16进制））
# 8：特殊数字（0o77（8进制））
i = n
type = 0
while i < len(str):
if type == 0: # 初始态
if str[i] == ' ': # 空格跳过
n += 1
i += 1
continue
elif str[i] == '\0' or str[i] == '\n': # 是结束
return
elif ('a' <= str[i] <= 'z') or ('A' <= str[i] <= 'Z'):
type = 1 # 是字母，
elif str[i] == '0':
type = 6 # 是数字，开头0，16进制或者8进制）
elif '1' <= str[i] <= '9':
type = 3 # 是数字，常数
else:
type = belong_to(str[i], 4)
if type > 0: # 是运算符
# 是能跟=号的运算符，后面是=号
if type == 2 and str[i + 1] == '=':
i = i + 1 # 结束位置后移
output(str, n, i, 4) # 输出 + 递归 + 结束
scan(str, i + 1)
return
elif belong_to(str[i], 5): # 是分隔符
output(str, n, i, 5) # 输出 + 递归 + 结束
scan(str, i + 1)
return
else:
print("失败:", str[i])
return
elif type == 1: # 关键字或标识符
if not (('a' <= str[i] <= 'z') or ('A' <= str[i] <= 'Z')): # 不是字母了
if '0' <= str[i] <= '9': # 是数字,只能是标识符
type = 2
else: # 非字母数字
type = iskeywords(str, n, i)
output(str, n, i - 1, type) # 输出 + 递归 + 结束
scan(str, i)
return
elif type == 2: # 标识符
if not (('a' <= str[i] <= 'z') or ('A' <= str[i] <= 'Z')):
# 不是字母了
if not ('0' <= str[i] <= '9'):
# 不是数字
output(str, n, i - 1, type) # 输出 + 递归 + 结束
scan(str, i)
return
elif type == 3:
if not ('0' <= str[i] <= '9'):
# 不是数字
output(str, n, i - 1, type) # 输出 + 递归 + 结束
scan(str, i)
return
elif type == 6:
if str[i] == 'x': # 16进制
type = 7
elif str[i] == 'o': # 8进制
type = 8
elif str[i] == ' ': # 就一个0
output(str, n, i - 1, type) # 输出 + 递归 + 结束
scan(str, i)
return
else:
print("%d失败" % type)
return
elif type == 7: # 16进制
if not (('0' <= str[i] <= '9') or ('a' <= str[i] <= 'f')):
# 不是16数字
output(str, n, i - 1, 3) # 输出 + 递归 + 结束
scan(str, i)
return
elif type == 8: # 8进制
if not ('0' <= str[i] <= '7'):
# 不是8数字
output(str, n, i - 1, 3) # 输出 + 递归 + 结束
scan(str, i)
return
else:
print("%d失败" % type)
return
i += 1
# 递归下降分析程序部分=====================================================================
# =====================================================================================
# 经过处理后的文法如下:
# S->id=E|if C then S|while C do S; id if while ;
# C->EC'; ( id int then do
# E->TE'; ( id int > = < ) ;
# T->FT'; ( id int + - > = < ) ;
# F->(E)|id|int; ( id int * / + - > = < ) ;
# E'->+TE'|-TE'|; + - e > = < ) ;
# T'->*FT'|/FT'|; * / e + - > = < ) ;
# C'->>E|=E| = < then do
# 由于函数名不能有‘所以里面的’由1代替
def Parse():
def ParseS(): # S的分析子程序 S->id=E|if C then S|while C do S; id if while ;
global lookahead, parseerror
if parseerror:
return
elif lookahead[0] == 2: # id=E
MatchToken(2)
MatchToken('=')
ParseE()
elif lookahead[1] == 'if': # if C then S
MatchToken('if')
ParseC()
MatchToken('then')
ParseS()
elif lookahead[1] == 'while': # while C do S
MatchToken('while')
ParseC()
MatchToken('do')
ParseS()
else:
print("S 错误")
parseerror = 1
# exit(0)
def ParseC(): # C的分析子程序 C->EC'; ( id int then do
global lookahead, parseerror
if parseerror:
return
elif lookahead[1] == '(' or lookahead[0] == 2 or lookahead[0] == 3: # EC'
ParseE()
ParseC1()
else:
print("C 错误")
parseerror = 2
# exit(0)
def ParseE(): # E的分析子程序 E->TE'; ( id int > = < ) ;
global lookahead, parseerror
if parseerror:
return
elif lookahead[1] == '(' or lookahead[0] == 2 or lookahead[0] == 3: # TE'
ParseT()
ParseE1()
else:
print("E 错误")
parseerror = 3
# exit(0)
def ParseT(): # T的分析子程序 T->FT'; ( id int + - > = < ) ; then do
global lookahead, parseerror
if parseerror:
return
elif lookahead[1] == '(' or lookahead[0] == 2 or lookahead[0] == 3: # FT'
ParseF()
ParseT1()
else:
print("T 错误")
parseerror = 4
# exit(0)
def ParseF(): # F的分析子程序 F->(E)|id|int; ( id int * / + - > = < ) ; then do
global lookahead, parseerror
if parseerror:
return
elif lookahead[1] == '(': # (E)
MatchToken('(')
ParseE()
MatchToken(')')
elif lookahead[0] == 2: # id
MatchToken(2)
elif lookahead[0] == 3: # int
MatchToken(3)
else:
print("F 错误")
parseerror = 5
# exit(0)
def ParseE1(): # E'的分析子程序 E'->+TE'|-TE'|; + - e > = < ) ; then do
global lookahead, parseerror
if parseerror:
return
elif lookahead[1] == '+': # +TE'
MatchToken('+')
ParseT()
ParseE1()
elif lookahead[1] == '-': # -TE'
MatchToken('-')
ParseT()
ParseE1()
elif lookahead[1] == ')' or lookahead[1] == ';' \
or lookahead[1] == '>' or lookahead[1] == '=' or lookahead[1] == '<' or \
lookahead[1] == 'then' or lookahead[1] == 'do':
pass
else:
print("E1 错误")
parseerror = 5
# exit(0)
def ParseT1(): # T'的分析子程序 T'->*FT'|/FT'|; * / e + - > = < ) ; then do
global lookahead, parseerror
if parseerror:
return
elif lookahead[1] == '*': # *FT'
MatchToken('*')
ParseF()
ParseT1()
elif lookahead[1] == '/': # /FT'
MatchToken('/')
ParseF()
ParseT1()
elif lookahead[1] == '+' or lookahead[1] == '-' or lookahead[1] == ')' or lookahead[1] == ';' or \
lookahead[1] == '>' or lookahead[1] == '=' or lookahead[1] == '<' or \
lookahead[1] == 'then' or lookahead[1] == 'do':
pass
else:
print("T1 错误")
parseerror = 5
# exit(0)
def ParseC1(): # C'的分析子程序 C'->>E|=E| = < then do
global lookahead, parseerror
if parseerror:
return
elif lookahead[1] == '>':
MatchToken('>')
ParseE()
elif lookahead[1] == '=':
MatchToken('=')
ParseE()
elif lookahead[1] == '<':
MatchToken('<')
ParseE()
else:
print("C1 错误")
parseerror = 5
# exit(0)
def MatchToken(need_type):
global lookahead, parseerror
mate = 0
if parseerror:
return
elif isinstance(need_type, int): # 输入的是int
if lookahead[0] == need_type: # 输入的和需要的相同
mate = 1
elif lookahead[1] == need_type: # 匹配的是字符串
mate = 1
if mate:
lookahead = GetToken() # 读入下一个
else:
print("需要", need_type, "实际", lookahead, "匹配错误")
parseerror = 6
# exit(0)
def GetToken():
global program, lookahead
return program.pop(0)
global program, lookahead, parseerror
parseerror = 0 # 错误标记
lookahead = program.pop(0)
ParseS()
if parseerror == 0:
print("正确")
file = "program.txt"
file = open(file) # 读取文件
while i := file.readline():
program = [] # 记录读到的句子
scan(i, 0)
print(i[:-1])
print(program)
Parse()
file.close()
3.根据语义，修改递归子程序，使其能生成中间代码
这里新增了一个叫NonTerminal的类，用来盛放继承属性和综合属性，最后输出综合属性。
# scan 部分=============================================================================
# =====================================================================================
# 输出结果
def output(str, a, b, type):
global program
program.append([type, str[a:b + 1]])
# 判断字符串一部分是否属于关键字
# 是返回1不是返回2
def iskeywords(str, a, b):
# 关键字
keywords = {"if", "int", "for", "while", "do", "return", "break", "continue", 'then'}
s = str[a:b] # 拷贝字符
if s in keywords: # 判断是否存在，存在返回1，否则返回2
return 1
else:
return 2
# 判断字符是否属于运算符或分隔符的一部分。
# 不是返回0，是返回1，是且后面能跟=号返回2
def belong_to(str, type):
if type == 4: # 选择运算符
library = "+-*/=>= 4:
return 2
else:
return 1
return 0
# 递归的词法分析函数，读入一行str字符串，初始位置 n = 0
# 分离+判断，打印输出类型
# 由之前的c语言版本改写而成
def scan(str, n):
# 7 种类型(最后输出1 - 5)
# -1
# 0: 初始
# 1: 关键字, 在keywords中
# 2: 标识符
# 3: 常数(无符号整型)
# 4: 运算符和界符:+ - * / = > < >= <= !=
# 5: 分隔符:, ; {}()
# 6: 特殊数字（0x64 或者0o77（16进制或者8进制））开始判断
# 7：特殊数字（0xa（16进制））
# 8：特殊数字（0o77（8进制））
i = n
type = 0
while i < len(str):
if type == 0: # 初始态
if str[i] == ' ': # 空格跳过
n += 1
i += 1
continue
elif str[i] == '\0' or str[i] == '\n': # 是结束
return
elif ('a' <= str[i] <= 'z') or ('A' <= str[i] <= 'Z'):
type = 1 # 是字母，
elif str[i] == '0':
type = 6 # 是数字，开头0，16进制或者8进制）
elif '1' <= str[i] <= '9':
type = 3 # 是数字，常数
else:
type = belong_to(str[i], 4)
if type > 0: # 是运算符
# 是能跟=号的运算符，后面是=号
if type == 2 and str[i + 1] == '=':
i = i + 1 # 结束位置后移
output(str, n, i, 4) # 输出 + 递归 + 结束
scan(str, i + 1)
return
elif belong_to(str[i], 5): # 是分隔符
output(str, n, i, 5) # 输出 + 递归 + 结束
scan(str, i + 1)
return
else:
print("失败:", str[i])
return
elif type == 1: # 关键字或标识符
if not (('a' <= str[i] <= 'z') or ('A' <= str[i] <= 'Z')): # 不是字母了
if '0' <= str[i] <= '9': # 是数字,只能是标识符
type = 2
else: # 非字母数字
type = iskeywords(str, n, i)
output(str, n, i - 1, type) # 输出 + 递归 + 结束
scan(str, i)
return
elif type == 2: # 标识符
if not (('a' <= str[i] <= 'z') or ('A' <= str[i] <= 'Z')):
# 不是字母了
if not ('0' <= str[i] <= '9'):
# 不是数字
output(str, n, i - 1, type) # 输出 + 递归 + 结束
scan(str, i)
return
elif type == 3:
if not ('0' <= str[i] <= '9'):
# 不是数字
output(str, n, i - 1, type) # 输出 + 递归 + 结束
scan(str, i)
return
elif type == 6:
if str[i] == 'x': # 16进制
type = 7
elif str[i] == 'o': # 8进制
type = 8
elif str[i] == ' ': # 就一个0
output(str, n, i - 1, type) # 输出 + 递归 + 结束
scan(str, i)
return
else:
print("%d失败" % type)
return
elif type == 7: # 16进制
if not (('0' <= str[i] <= '9') or ('a' <= str[i] <= 'f')):
# 不是16数字
output(str, n, i - 1, 3) # 输出 + 递归 + 结束
scan(str, i)
return
elif type == 8: # 8进制
if not ('0' <= str[i] <= '7'):
# 不是8数字
output(str, n, i - 1, 3) # 输出 + 递归 + 结束
scan(str, i)
return
else:
print("%d失败" % type)
return
i += 1
# 递归下降分析程序部分=====================================================================
# =====================================================================================
# 经过处理后的文法如下:
# S->id=E|if C then S|while C do S; id if while ;
# C->EC'; ( id int then do
# E->TE'; ( id int > = < ) ; then do
# T->FT'; ( id int + - > = < ) ; then do
# F->(E)|id|int; ( id int * / + - > = < ) ; then do
# E'->+TE'|-TE'|; + - e > = < ) ; then do
# T'->*FT'|/FT'|; * / e + - > = < ) ; then do
# C'->>E|=E| = < then do
class NonTerminal:
def __init__(self):
self.begin = ''
self.place = ''
self.next = ''
self.true = ''
self.false = ''
self.code = []
# 由于函数名不能有‘所以里面的’由1代替
def Parse():
def ParseS(S): # S的分析子程序 S->id=E|if C then S|while C do S; id if while ;
global lookahead, parseerror
if parseerror:
return
elif lookahead[0] == 2: # id=E
id = MatchToken(2)
MatchToken('=')
E = NonTerminal()
ParseE(E)
S.code = E.code
S.code = [E.code, id.place, " := ", E.place,'\n','goto ', S.next, '\n']
elif lookahead[1] == 'if': # if C then S
MatchToken('if')
C = NonTerminal()
C.true = newlable()
C.false = S.next
ParseC(C)
MatchToken('then')
S1 = NonTerminal()
S1.begin = C.true
S1.next = S.next
ParseS(S1)
S.code = [C.code, C.true, ':\n', S1.code, ]
elif lookahead[1] == 'while': # while C do S
MatchToken('while')
C = NonTerminal()
C.true = newlable()
C.false = S.next
ParseC(C)
MatchToken('do')
S1 = NonTerminal()
S1.begin = C.true
S1.next = S.begin
ParseS(S1)
S.code = [C.code, C.true, ':\n', S1.code, ]
else:
print("S 错误")
parseerror = 1
# exit(0)
def ParseC(C): # C的分析子程序 C->EC'; ( id int then do
global lookahead, parseerror
if parseerror:
return
elif lookahead[1] == '(' or lookahead[0] == 2 or lookahead[0] == 3: # EC'
E = NonTerminal()
ParseE(E)
C1 = NonTerminal()
ParseC1(C1)
C.code = [E.code, C1.code, 'if ', E.place, C1.place, ' goto ', C.true, '\n', ' goto ', C.false, '\n']
else:
print("C 错误")
parseerror = 2
# exit(0)
def ParseE(E): # E的分析子程序 E->TE'; ( id int > = < ) ;
global lookahead, parseerror
if parseerror:
return
elif lookahead[1] == '(' or lookahead[0] == 2 or lookahead[0] == 3: # TE'
T = NonTerminal()
ParseT(T)
E1 = NonTerminal()
ParseE1(E1)
if len(E1.code) > 0: # 有东西
E.place = newtemp()
E.code = [T.code, E1.code, E.place, ' := ', T.place, E1.place, '\n']
else:
E.place = T.place
E.code = [T.code]
else:
print("E 错误")
parseerror = 3
# exit(0)
def ParseT(T): # T的分析子程序 T->FT'; ( id int + - > = < ) ; then do
global lookahead, parseerror
if parseerror:
return
elif lookahead[1] == '(' or lookahead[0] == 2 or lookahead[0] == 3: # FT'
F = NonTerminal()
ParseF(F)
T1 = NonTerminal()
ParseT1(T1)
if len(T1.code) > 0: # 有东西
T.place = newtemp()
T.code = [F.code, T1.code, T.place, ' := ', F.place, T1.place, '\n']
else:
T.place = F.place
T.code = [F.code]
else:
print("T 错误")
parseerror = 4
# exit(0)
def ParseF(F): # F的分析子程序 F->(E)|id|int; ( id int * / + - > = < ) ; then do
global lookahead, parseerror
if parseerror:
return
elif lookahead[1] == '(': # (E)
MatchToken('(')
E = NonTerminal()
ParseE(E)
MatchToken(')')
F.place = E.place
F.code = E.code
elif lookahead[0] == 2: # id
E = MatchToken(2)
F.place = E.place
F.code = E.code
elif lookahead[0] == 3: # int
E = MatchToken(3)
F.place = E.place
F.code = E.code
else:
print("F 错误")
parseerror = 5
# exit(0)
def ParseE1(E1): # E'的分析子程序 E'->+TE'|-TE'|; + - e > = < ) ; then do
global lookahead, parseerror
if parseerror:
return
elif lookahead[1] == '+': # +TE'
MatchToken('+')
T = NonTerminal()
ParseT(T)
E2 = NonTerminal()
ParseE1(E2)
E1.place = '+' + T.place
E1.code = [T.code, E2.code, ]
elif lookahead[1] == '-': # -TE'
MatchToken('-')
T = NonTerminal()
ParseT(T)
E2 = NonTerminal()
ParseE1(E2)
E1.place = '-' + T.place
E1.code = [T.code, E2.code, ]
elif lookahead[1] == ')' or lookahead[1] == ';' \
or lookahead[1] == '>' or lookahead[1] == '=' or lookahead[1] == '<' or \
lookahead[1] == 'then' or lookahead[1] == 'do':
pass
else:
print("E1 错误")
parseerror = 5
# exit(0)
def ParseT1(T1): # T'的分析子程序 T'->*FT'|/FT'|; * / e + - > = < ) ; then do
global lookahead, parseerror
if parseerror:
return
elif lookahead[1] == '*': # *FT'
MatchToken('*')
F = NonTerminal()
ParseF(F)
T2 = NonTerminal()
ParseT1(T2)
T1.place = '*' + F.place
T1.code = [F.code, T2.code, ]
elif lookahead[1] == '/': # /FT'
MatchToken('/')
F = NonTerminal()
ParseF(F)
T2 = NonTerminal()
ParseT1(T2)
T1.place = '/' + F.place
T1.code = [F.code, '\n', T2.code, ]
elif lookahead[1] == '+' or lookahead[1] == '-' or lookahead[1] == ')' or lookahead[1] == ';' or \
lookahead[1] == '>' or lookahead[1] == '=' or lookahead[1] == '<' or \
lookahead[1] == 'then' or lookahead[1] == 'do':
pass
else:
print("T1 错误")
parseerror = 5
# exit(0)
def ParseC1(C1): # C'的分析子程序 C'->>E|=E| = < then do
global lookahead, parseerror
if parseerror:
return
elif lookahead[1] == '>':
MatchToken('>')
E = NonTerminal()
ParseE(E)
C1.place = '>' + E.place
C1.code = [E.code]
elif lookahead[1] == '=':
MatchToken('=')
E = NonTerminal()
ParseE(E)
C1.place = '=' + E.place
C1.code = [E.code]
elif lookahead[1] == '<':
MatchToken('<')
E = NonTerminal()
ParseE(E)
C1.place = '<' + E.place
C1.code = [E.code]
else:
print("C1 错误")
parseerror = 5
# exit(0)
def MatchToken(need_type):
global lookahead, parseerror
A = NonTerminal()
mate = 0
if parseerror:
return
elif isinstance(need_type, int): # 输入的是int
if lookahead[0] == need_type: # 输入的和需要的相同
if need_type == 2:
A.place = lookahead[1]
if need_type == 3:
A.place = str(eval(lookahead[1]))
A.code = ['']
mate = 1
lookahead = GetToken() # 读入下一个
return A
elif lookahead[1] == need_type: # 匹配的是字符串
mate = 1
if mate:
lookahead = GetToken() # 读入下一个
else:
print("需要", need_type, "实际", lookahead, "匹配错误")
parseerror = 6
# exit(0)
def GetToken():
global program, lookahead
return program.pop(0)
def newlable():
global lable_count
lable_count += 1
return "L" + str(lable_count)
def newtemp():
global z_temp
z_temp += 1
return "z" + str(z_temp)
def Print_Place(code):
s = ''
for i in code:
if isinstance(i, list):
s += Print_Place(i)
else:
s = s + i
return s
global program, parseerror, lookahead, lable_count, z_temp
lable_count = 0 # 块号
z_temp = 0
parseerror = 0 # 错误标记
lookahead = program.pop(0)
S = NonTerminal()
S.begin = newlable()
S.next = 'L0'
try:
ParseS(S)
if parseerror == 0:
print("正确")
print("中间代码：")
print(S.begin,':')
print(Print_Place(S.code))
print("L0: # S->next")
except:
print("错误")
file = "program.txt"
file = open(file) # 读取文件
while i := file.readline():
print("# =====================================================================================")
program = [] # 记录读到的句子
scan(i, 0)
print(i[:-1])
print(program)
Parse()
file.close()
输入示例：
在文件"program.txt"中
a = 15*8-25;
while a>3 do a=a+3;
if s>0xa then s=s+1;
while a=0o16 do if a>5 then a = a+1;
while a>5 do if a=5 then while a<8 do a=a+1;
while (a3+15)>0xa do if x2>0o7 then while y输出示例：
# =====================================================================================
a = 15*8-25;
[[2, 'a'], [4, '='], [3, '15'], [4, '*'], [3, '8'], [4, '-'], [3, '25'], [5, ';']]
正确
中间代码：
L1 :
z1 := 15*8
z2 := z1-25
a := z2
goto L0
L0: # S->next
# =====================================================================================
while a>3 do a=a+3;
[[1, 'while'], [2, 'a'], [4, '>'], [3, '3'], [1, 'do'], [2, 'a'], [4, '='], [2, 'a'], [4, '+'], [3, '3'], [5, ';']]
正确
中间代码：
L1 :
if a>3 goto L2
goto L0
L2:
z1 := a+3
a := z1
goto L1
L0: # S->next
# =====================================================================================
if s>0xa then s=s+1;
[[1, 'if'], [2, 's'], [4, '>'], [3, '0xa'], [1, 'then'], [2, 's'], [4, '='], [2, 's'], [4, '+'], [3, '1'], [5, ';']]
正确
中间代码：
L1 :
if s>10 goto L2
goto L0
L2:
z1 := s+1
s := z1
goto L0
L0: # S->next
# =====================================================================================
while a=0o16 do if a>5 then a = a+1;
[[1, 'while'], [2, 'a'], [4, '='], [3, '0o16'], [1, 'do'], [1, 'if'], [2, 'a'], [4, '>'], [3, '5'], [1, 'then'], [2, 'a'], [4, '='], [2, 'a'], [4, '+'], [3, '1'], [5, ';']]
正确
中间代码：
L1 :
if a=14 goto L2
goto L0
L2:
if a>5 goto L3
goto L1
L3:
z1 := a+1
a := z1
goto L1
L0: # S->next
# =====================================================================================
while a>5 do if a=5 then while a<8 do a=a+1;
[[1, 'while'], [2, 'a'], [4, '>'], [3, '5'], [1, 'do'], [1, 'if'], [2, 'a'], [4, '='], [3, '5'], [1, 'then'], [1, 'while'], [2, 'a'], [4, '<'], [3, '8'], [1, 'do'], [2, 'a'], [4, '='], [2, 'a'], [4, '+'], [3, '1'], [5, ';']]
正确
中间代码：
L1 :
if a>5 goto L2
goto L0
L2:
if a=5 goto L3
goto L1
L3:
if a<8 goto L4
goto L1
L4:
z1 := a+1
a := z1
goto L3
L0: # S->next
# =====================================================================================
while (a3+15)>0xa do if x2>0o7 then while y'], [3, '0xa'], [1, 'do'], [1, 'if'], [2, 'x2'], [4, '>'], [3, '0o7'], [1, 'then'], [1, 'while'], [2, 'y'], [4, '<'], [2, 'z'], [1, 'do'], [2, 'y'], [4, '='], [2, 'x'], [4, '*'], [2, 'y'], [4, '/'], [2, 'z'], [5, ';']]
正确
中间代码：
L1 :
z1 := a3+15
if z1>10 goto L2
goto L0
L2:
if x2>7 goto L3
goto L1
L3:
if ynext