我使用treetop编写了一个解析器,它成功地生成了一个解析树,其中的一部分在下面复制。
SyntaxNode offset=4043, " ":
SyntaxNode offset=4043, " "
SyntaxNode offset=4044, " "
SyntaxNode offset=4045, " "
StringLiteral+StringLiteral1 offset=4046, "\"MS Sans Serif\"":
SyntaxNode offset=4046, "\""
SyntaxNode offset=4047, "MS Sans Serif":
SyntaxNode+StringLiteral0 offset=4047, "M":
SyntaxNode offset=4047, ""
SyntaxNode offset=4047, "M"
SyntaxNode+StringLiteral0 offset=4048, "S":
SyntaxNode offset=4048, ""
SyntaxNode offset=4048, "S"
SyntaxNode+StringLiteral0 offset=4049, " ":
SyntaxNode offset=4049, ""
SyntaxNode offset=4049, " "
SyntaxNode+StringLiteral0 offset=4050, "S":
SyntaxNode offset=4050, ""
SyntaxNode offset=4050, "S"
SyntaxNode+StringLiteral0 offset=4051, "a":
SyntaxNode offset=4051, ""
SyntaxNode offset=4051, "a"
SyntaxNode+StringLiteral0 offset=4052, "n":
SyntaxNode offset=4052, ""
SyntaxNode offset=4052, "n"
SyntaxNode+StringLiteral0 offset=4053, "s":
SyntaxNode offset=4053, ""
SyntaxNode offset=4053, "s"
SyntaxNode+StringLiteral0 offset=4054, " ":
SyntaxNode offset=4054, ""
SyntaxNode offset=4054, " "
SyntaxNode+StringLiteral0 offset=4055, "S":
SyntaxNode offset=4055, ""
SyntaxNode offset=4055, "S"
SyntaxNode+StringLiteral0 offset=4056, "e":
SyntaxNode offset=4056, ""
SyntaxNode offset=4056, "e"
SyntaxNode+StringLiteral0 offset=4057, "r":
SyntaxNode offset=4057, ""
SyntaxNode offset=4057, "r"
SyntaxNode+StringLiteral0 offset=4058, "i":
SyntaxNode offset=4058, ""
SyntaxNode offset=4058, "i"
SyntaxNode+StringLiteral0 offset=4059, "f":
SyntaxNode offset=4059, ""
SyntaxNode offset=4059, "f"
SyntaxNode offset=4060, "\""
现在我有了这棵树,我不知道如何过滤它,以便只处理与特定规则匹配的特定节点。
我想用一个标识符替换字符串文字,该标识符引用字符串文件中的字符串。
cool_parser.treetop
rule string_literal
'"' (!'"' . / '""')* '"'
end
require 'treetop'
# Load the grammar
Treetop.load 'cool'
class Parser
# Create the parser
@@parser = CoolParser.new
def self.parse(data)
# Pass the data over to the parser instance
tree = @@parser.parse(data)
if(tree.nil?)
raise Exception, "Parse error at offset: #{@@parser.index}"
end
return tree
end
end
tree = Parser.parse(File.open("myfile.txt").read)
puts tree.inspect