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view ply-3.8/example/yply/yparse.py @ 12493:885661512b17 draft
<int-e> le//rn schwartzian//In 1987, Yogurt introduced a better way to rank Schwartz users: Rather than holding an annual tournament, users would take a series of standardized tests adminstered by official Schwartz centers, and would then be ranked according to the results. This lead to the Schwartzian transform because it allowed many more users to be ranked.
author | HackEso <hackeso@esolangs.org> |
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date | Fri, 12 Jan 2024 07:24:55 +0000 |
parents | 343ff337a19b |
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# parser for Unix yacc-based grammars # # Author: David Beazley (dave@dabeaz.com) # Date : October 2, 2006 import ylex tokens = ylex.tokens from ply import * tokenlist = [] preclist = [] emit_code = 1 def p_yacc(p): '''yacc : defsection rulesection''' def p_defsection(p): '''defsection : definitions SECTION | SECTION''' p.lexer.lastsection = 1 print "tokens = ", repr(tokenlist) print print "precedence = ", repr(preclist) print print "# -------------- RULES ----------------" print def p_rulesection(p): '''rulesection : rules SECTION''' print "# -------------- RULES END ----------------" print_code(p[2],0) def p_definitions(p): '''definitions : definitions definition | definition''' def p_definition_literal(p): '''definition : LITERAL''' print_code(p[1],0) def p_definition_start(p): '''definition : START ID''' print "start = '%s'" % p[2] def p_definition_token(p): '''definition : toktype opttype idlist optsemi ''' for i in p[3]: if i[0] not in "'\"": tokenlist.append(i) if p[1] == '%left': preclist.append(('left',) + tuple(p[3])) elif p[1] == '%right': preclist.append(('right',) + tuple(p[3])) elif p[1] == '%nonassoc': preclist.append(('nonassoc',)+ tuple(p[3])) def p_toktype(p): '''toktype : TOKEN | LEFT | RIGHT | NONASSOC''' p[0] = p[1] def p_opttype(p): '''opttype : '<' ID '>' | empty''' def p_idlist(p): '''idlist : idlist optcomma tokenid | tokenid''' if len(p) == 2: p[0] = [p[1]] else: p[0] = p[1] p[1].append(p[3]) def p_tokenid(p): '''tokenid : ID | ID NUMBER | QLITERAL | QLITERAL NUMBER''' p[0] = p[1] def p_optsemi(p): '''optsemi : ';' | empty''' def p_optcomma(p): '''optcomma : ',' | empty''' def p_definition_type(p): '''definition : TYPE '<' ID '>' namelist optsemi''' # type declarations are ignored def p_namelist(p): '''namelist : namelist optcomma ID | ID''' def p_definition_union(p): '''definition : UNION CODE optsemi''' # Union declarations are ignored def p_rules(p): '''rules : rules rule | rule''' if len(p) == 2: rule = p[1] else: rule = p[2] # Print out a Python equivalent of this rule embedded = [ ] # Embedded actions (a mess) embed_count = 0 rulename = rule[0] rulecount = 1 for r in rule[1]: # r contains one of the rule possibilities print "def p_%s_%d(p):" % (rulename,rulecount) prod = [] prodcode = "" for i in range(len(r)): item = r[i] if item[0] == '{': # A code block if i == len(r) - 1: prodcode = item break else: # an embedded action embed_name = "_embed%d_%s" % (embed_count,rulename) prod.append(embed_name) embedded.append((embed_name,item)) embed_count += 1 else: prod.append(item) print " '''%s : %s'''" % (rulename, " ".join(prod)) # Emit code print_code(prodcode,4) print rulecount += 1 for e,code in embedded: print "def p_%s(p):" % e print " '''%s : '''" % e print_code(code,4) print def p_rule(p): '''rule : ID ':' rulelist ';' ''' p[0] = (p[1],[p[3]]) def p_rule2(p): '''rule : ID ':' rulelist morerules ';' ''' p[4].insert(0,p[3]) p[0] = (p[1],p[4]) def p_rule_empty(p): '''rule : ID ':' ';' ''' p[0] = (p[1],[[]]) def p_rule_empty2(p): '''rule : ID ':' morerules ';' ''' p[3].insert(0,[]) p[0] = (p[1],p[3]) def p_morerules(p): '''morerules : morerules '|' rulelist | '|' rulelist | '|' ''' if len(p) == 2: p[0] = [[]] elif len(p) == 3: p[0] = [p[2]] else: p[0] = p[1] p[0].append(p[3]) # print "morerules", len(p), p[0] def p_rulelist(p): '''rulelist : rulelist ruleitem | ruleitem''' if len(p) == 2: p[0] = [p[1]] else: p[0] = p[1] p[1].append(p[2]) def p_ruleitem(p): '''ruleitem : ID | QLITERAL | CODE | PREC''' p[0] = p[1] def p_empty(p): '''empty : ''' def p_error(p): pass yacc.yacc(debug=0) def print_code(code,indent): if not emit_code: return codelines = code.splitlines() for c in codelines: print "%s# %s" % (" "*indent,c)