answer:由于ST语言比较特殊，且Ply不是针对该语言设计的解析器，因此实现的难度会比较大。以下是一个简单的实现，仅供参考。 需要注意的是，以下代码仅支持基本的语法，仍有很多错误没有考虑到。 ```python import ply.lex as lex import ply.yacc as yacc # 定义ST语言的关键字 reserved = { 'VAR': 'VAR', 'END_VAR': 'END_VAR', 'IF': 'IF', 'THEN': 'THEN', 'ELSE': 'ELSE', 'END_IF': 'END_IF', 'CASE': 'CASE', 'OF': 'OF', 'END_CASE': 'END_CASE', 'WHILE': 'WHILE', 'DO': 'DO', 'END_WHILE': 'END_WHILE', 'FOR': 'FOR', 'TO': 'TO', 'BY': 'BY', 'DO': 'DO', 'END_FOR': 'END_FOR', 'REPEAT': 'REPEAT', 'UNTIL': 'UNTIL', 'END_REPEAT': 'END_REPEAT', 'AND': 'AND', 'OR': 'OR', 'XOR': 'XOR', 'NOT': 'NOT', 'MOD': 'MOD', 'DIV': 'DIV', 'TRUE': 'TRUE', 'FALSE': 'FALSE' } # 定义ST语言的标记符 tokens = [ 'IDENTIFIER', 'NUMBER', 'PLUS', 'MINUS', 'TIMES', 'DIVIDE', 'POWER', 'LPAREN', 'RPAREN', 'SEMI', 'COLON', 'COMMA', 'LT', 'LE', 'GT', 'GE', 'EQ', 'NE', 'AND', 'OR', 'XOR', 'NOT', 'MOD', 'DIV' ] + list(reserved.values()) # 定义ST语言的正则表达式 t_PLUS = r'+' t_MINUS = r'-' t_TIMES = r'*' t_DIVIDE = r'/' t_POWER = r'**' t_LPAREN = r'(' t_RPAREN = r')' t_SEMI = r';' t_COLON = r':' t_COMMA = r',' t_LT = r'<' t_LE = r'<=' t_GT = r'>' t_GE = r'>=' t_EQ = r'=' t_NE = r'<>' # 定义ST语言的特殊标记符 def t_NUMBER(t): r'd+' t.value = int(t.value) return t def t_IDENTIFIER(t): r'[a-zA-Z_][a-zA-Z0-9_]*' t.type = reserved.get(t.value.upper(), 'IDENTIFIER') return t t_AND = r'AND' t_OR = r'OR' t_XOR = r'XOR' t_NOT = r'NOT' t_MOD = r'MOD' t_DIV = r'DIV' # 忽略空白符 t_ignore = ' tr' # 忽略注释 def t_comment(t): r'#.*' pass # 记录行号 def t_newline(t): r'n+' t.lexer.lineno += len(t.value) # 错误处理 def t_error(t): print("Illegal character '%s'" % t.value[0]) t.lexer.skip(1) lexer = lex.lex() variables = {} # 定义ST语言的语法规则 def p_program(p): '''program : statement_list''' p[0] = ('PROGRAM', p[1]) def p_statement_list(p): '''statement_list : statement | statement_list statement''' if len(p) == 2: p[0] = [p[1]] else: p[0] = p[1] + [p[2]] def p_statement(p): '''statement : assignment_statement | if_statement | case_statement | while_statement | for_statement | repeat_statement''' p[0] = p[1] def p_assignment_statement(p): '''assignment_statement : IDENTIFIER COLON assignment_expression SEMI''' variables[p[1]] = p[3] p[0] = ('ASSIGNMENT', p[1], p[3]) def p_assignment_expression(p): '''assignment_expression : logical_or_expression''' p[0] = p[1] def p_logical_or_expression(p): '''logical_or_expression : logical_and_expression | logical_or_expression OR logical_and_expression''' if len(p) == 2: p[0] = p[1] else: p[0] = ('OR', p[1], p[3]) def p_logical_and_expression(p): '''logical_and_expression : bit_or_expression | logical_and_expression AND bit_or_expression''' if len(p) == 2: p[0] = p[1] else: p[0] = ('AND', p[1], p[3]) def p_bit_or_expression(p): '''bit_or_expression : bit_xor_expression | bit_or_expression '|' bit_xor_expression''' if len(p) == 2: p[0] = p[1] else: p[0] = ('BIT_OR', p[1], p[3]) def p_bit_xor_expression(p): '''bit_xor_expression : bit_and_expression | bit_xor_expression XOR bit_and_expression''' if len(p) == 2: p[0] = p[1] else: p[0] = ('BIT_XOR', p[1], p[3]) def p_bit_and_expression(p): '''bit_and_expression : equality_expression | bit_and_expression '&' equality_expression''' if len(p) == 2: p[0] = p[1] else: p[0] = ('BIT_AND', p[1], p[3]) def p_equality_expression(p): '''equality_expression : relational_expression | equality_expression EQ relational_expression | equality_expression NE relational_expression''' if len(p) == 2: p[0] = p[1] elif p[2] == '=': p[0] = ('EQ', p[1], p[3]) else: p[0] = ('NE', p[1], p[3]) def p_relational_expression(p): '''relational_expression : additive_expression | relational_expression LT additive_expression | relational_expression LE additive_expression | relational_expression GT additive_expression | relational_expression GE additive_expression''' if len(p) == 2: p[0] = p[1] elif p[2] == '<': p[0] = ('LT', p[1], p[3]) elif p[2] == '<=': p[0] = ('LE', p[1], p[3]) elif p[2] == '>': p[0] = ('GT', p[1], p[3]) else: p[0] = ('GE', p[1], p[3]) def p_additive_expression(p): '''additive_expression : multiplicative_expression | additive_expression PLUS multiplicative_expression | additive_expression MINUS multiplicative_expression''' if len(p) == 2: p[0] = p[1] elif p[2] == '+': p[0] = ('ADD', p[1], p[3]) else: p[0] = ('SUB', p[1], p[3]) def p_multiplicative_expression(p): '''multiplicative_expression : power_expression | multiplicative_expression TIMES power_expression | multiplicative_expression DIVIDE power_expression''' if len(p) == 2: p[0] = p[1] elif p[2] == '*': p[0] = ('MUL', p[1], p[3]) else: p[0] = ('DIV', p[1], p[3]) def p_power_expression(p): '''power_expression : unary_expression | power_expression POWER unary_expression''' if len(p) == 2: p[0] = p[1] else: p[0] = ('POW', p[1], p[3]) def p_unary_expression(p): '''unary_expression : primary_expression | MINUS primary_expression | NOT primary_expression''' if len(p) == 2: p[0] = p[1] elif p[1] == '-': p[0] = ('NEG', p[2]) else: p[0] = ('NOT', p[2]) def p_primary_expression(p): '''primary_expression : IDENTIFIER | NUMBER | LPAREN assignment_expression RPAREN''' if len(p) == 2: if isinstance(p[1], str): try: p[0] = variables[p[1]] except KeyError: print("Variable '%s' not defined" % p[1]) else: p[0] = p[1] else: p[0] = p[2] def p_if_statement(p): '''if_statement : IF logical_or_expression THEN statement_list ELSE statement_list END_IF''' p[0] = ('IF', p[2], p[4], p[6]) def p_case_statement(p): '''case_statement : CASE assignment_expression OF case_list END_CASE''' p[0] = ('CASE', p[2], p[4]) def p_case_list(p): '''case_list : case_item | case_list case_item''' if len(p) == 2: p[0] = [p[1]] else: p[0] = p[1] + [p[2]] def p_case_item(p): '''case_item : NUMBER COLON statement_list SEMI''' p[0] = (p[1], p[3]) def p_while_statement(p): '''while_statement : WHILE logical_or_expression DO statement_list END_WHILE''' p[0] = ('WHILE', p[2], p[4]) def p_for_statement(p): '''for_statement : FOR IDENTIFIER COLON assignment_expression TO assignment_expression | FOR IDENTIFIER COLON assignment_expression TO assignment_expression BY assignment_expression''' if len(p) == 8: p[0] = ('FOR', p[2], p[4], p[6]) else: p[0] = ('FOR', p[2], p[4], p[6], p[8]) def p_repeat_statement(p): '''repeat_statement : REPEAT statement_list UNTIL logical_or_expression SEMI''' p[0] = ('REPEAT', p[2], p[4]) def p_error(p): print("Syntax error in input!") parser = yacc.yacc() # 测试程序 if __name__ == '__main__': data = ''' VAR a: INT; b: INT; END_VAR a := 1; b := 2; IF a EQ b THEN b := a + b; a := b; ELSE a := b; END_IF CASE a OF 1: a := 2; 2: a := 3; ELSE a := 4; END_CASE WHILE a LT 5 DO a := a + 1; END_WHILE FOR i: = 1 TO 10 BY 2 DO a := a * i; END_FOR REPEAT a := a + 1; UNTIL a GE 100; ''' ast = parser.parse(data) print(ast)

answer:1. ¿Por qué no se puede jugar al escondite con una persona ciega? Porque no tiene sentido, ya que siempre pierden. 2. ¿Sabes cuántas personas murieron en el Titanic? Todas. 3. ¿Qué tienen en común las piñatas y los niños con cáncer? Que los dos están llenos de sorpresas. 4. ¿Qué diferencia hay entre un bebé y una naranja? Que a la naranja se le puede quitar la piel sin que llore. 5. ¿Cómo se llama un caníbal vegetariano? Un comilón de lechugas. 6. ¿Cómo se llama un tiburón que se niega a comer carne? Un tiburón vegano. 7. ¿Sabes por qué se llaman a los cementerios necrópolis? Porque es el lugar donde se guardan todos los cuerpos. 8. ¿Cuál es el animal que da la leche más rica? El burro, porque la toma directamente de la fuente. 9. ¿Cuál es la marca de autopartes preferida por los bomberos? Bosch, porque siempre están encendidos. 10. ¿Cómo se llama el pan que te ayuda a bajar de peso? El pan de molde, porque siempre que lo ves, te dan ganas de moldear tu cuerpo.

answer:Привет! Как я могу Вам помочь?

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