将 ANTLR 解析树转换为 JSON [英] Convert ANTLR parse tree to JSON
问题描述
我有一个有效的语法并且已经实现了一个监听器(在 Java 中).我可以在控制台中用缩进显示解析树,但是我想将它导出为 JSON 结构,以便它可以在任何通用查看器中使用.
I have a working grammar and have implemented a listener (in Java). I can display the parse tree in the console with indentation however what I would like is to export it to a JSON structure so that it can be used in any generic viewer.
是否有已经制作的方法可以做到这一点,还是我必须以某种方式完全从头开始创建 json 文件?
Is there an already made method that can do this or will I have to create the json file absolutely from scratch somehow?
谢谢!
PS:我还设法通过 TreeView 类在 Swing 中显示...
PS: I also managed to display in Swing via the TreeView class...
推荐答案
是否有已经制作的方法可以做到这一点,还是我必须以某种方式完全从头开始创建 json 文件?
Is there an already made method that can do this or will I have to create the json file absolutely from scratch somehow?
正如评论中已经提到的:不,在ANTLR的核心API中没有这样的方法.你将不得不推出自己的.
As already mentioned in the comments: no, there is no such method in the core API of ANTLR. You will have to roll your own.
我有一个用于调试的实用方法,可以将 ANTLR ParseTree
传输到 java.util.Map
中,该方法可以轻松转换为 JSON 对象.我很高兴在这里分享.
I have a utility method for debugging purposes that transfers an ANTLR ParseTree
into a java.util.Map
which can easily be transformed into a JSON object. I'm happy to share it here.
给定以下语法:
grammar Expression;
parse
: expr EOF
;
expr
: '(' expr ')' #nestedExpr
| '-' expr #unartyMinusExpr
| expr ( '*' | '/' | '%' ) expr #multExpr
| expr ( '+' | '-' ) expr #addExpr
| expr ( '>' | '>=' | '<' | '<=' ) expr #compareExpr
| expr ( '=' | '!=' ) expr #eqExpr
| expr AND expr #andExpr
| expr OR expr #orExpr
| function_call #functionCallExpr
| ID #idExpr
| NUMBER #numberExpr
| STRING #stringExpr
;
function_call
: ID args
;
args
: '(' ( expr ( ',' expr )* )? ')'
;
ADD : '+';
MINUS : '-';
MULT : '*';
DIV : '/';
MOD : '%';
OPAR : '(';
CPAR : ')';
LTE : '<=';
LT : '<';
GTE : '>=';
GT : '>';
EQ : '=';
NEQ : '!=';
AND : 'and';
OR : 'or';
NUMBER : ( [0-9]* '.' )? [0-9]+;
ID : [a-zA-Z_] [a-zA-Z_0-9]*;
STRING : '"' ~["\r\n]* '"';
NL : '\r'? '\n' | '\r';
SPACE : [ \t] -> skip;
和下面的 Main 类,它处理输入 (1 + 2) * 3
:
and the following Main class, which handles the input (1 + 2) * 3
:
public class Examples {
private static final Gson PRETTY_PRINT_GSON = new GsonBuilder().setPrettyPrinting().create();
private static final Gson GSON = new Gson();
public static String toJson(ParseTree tree) {
return toJson(tree, true);
}
public static String toJson(ParseTree tree, boolean prettyPrint) {
return prettyPrint ? PRETTY_PRINT_GSON.toJson(toMap(tree)) : GSON.toJson(toMap(tree));
}
public static Map<String, Object> toMap(ParseTree tree) {
Map<String, Object> map = new LinkedHashMap<>();
traverse(tree, map);
return map;
}
public static void traverse(ParseTree tree, Map<String, Object> map) {
if (tree instanceof TerminalNodeImpl) {
Token token = ((TerminalNodeImpl) tree).getSymbol();
map.put("type", token.getType());
map.put("text", token.getText());
}
else {
List<Map<String, Object>> children = new ArrayList<>();
String name = tree.getClass().getSimpleName().replaceAll("Context$", "");
map.put(Character.toLowerCase(name.charAt(0)) + name.substring(1), children);
for (int i = 0; i < tree.getChildCount(); i++) {
Map<String, Object> nested = new LinkedHashMap<>();
children.add(nested);
traverse(tree.getChild(i), nested);
}
}
}
public static void main(String[] args) {
String source = "(1 + 2) * 3";
ExpressionLexer lexer = new ExpressionLexer(CharStreams.fromString(source));
ExpressionParser parser = new ExpressionParser(new CommonTokenStream(lexer));
System.out.println(toJson(parser.parse()));
}
}
您将看到以下内容打印到您的控制台:
you will see the following printed to your console:
{
"parse": [
{
"multExpr": [
{
"nestedExpr": [
{
"type": 7,
"text": "("
},
{
"addExpr": [
{
"numberExpr": [
{
"type": 17,
"text": "1"
}
]
},
{
"type": 2,
"text": "+"
},
{
"numberExpr": [
{
"type": 17,
"text": "2"
}
]
}
]
},
{
"type": 8,
"text": ")"
}
]
},
{
"type": 4,
"text": "*"
},
{
"numberExpr": [
{
"type": 17,
"text": "3"
}
]
}
]
},
{
"type": -1,
"text": "\u003cEOF\u003e"
}
]
}
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