如何从Antlr4解析器中获取解析树？

发布于 2025-02-09 21:10:20 字数 1140 浏览 3 评论 0原文

我正在使用antlr4来解析SQL。我设法生成了解析器，似乎有效。

我现在坚持如何从解析器中获取一棵树。

string input="SELECT * FROM myTable";
ITokenSource lexer = new PlSqlLexer(new AntlrInputStream(input));
ITokenStream tokens = new CommonTokenStream(lexer);

var parser = new PlSqlParser(tokens, writerOutput, writerError);
parser.AddErrorListener(new ThrowExceptionErrorListener());
parser.BuildParseTree = true;
myTree = parser.# what method here #();

我看到我可以在某个时候使用sql_statement（）方法，sql_create_table（）均取决于SQL源内的内容。但是，我应该怎么知道在解析内容之前是什么类型呢？我期望有一种通用方法在树结构中创建对象，因此以后可以将其馈送到MyVisitor类并生成对象。如果我不使用正确的方法，我得到了访问者无法处理的无类型对象的树。

我在做什么错？

编辑：我正在使用

当我使用sql_script（）时，我得到了这个未类型的对象（我看不到弹出标签中的类型）

” “一个没有类型的对象”

输入是：

string input = @"
CREATE TABLE ot.persons(
    person_id NUMBER GENERATED BY DEFAULT AS IDENTITY,
    first_name VARCHAR2(50) NOT NULL,
    last_name VARCHAR2(50) NOT NULL,
    PRIMARY KEY(person_id)
);
";

原文

I'm using ANTLR4 to parse SQL. I managed to generate the parser and it seems to work.

I'm now stuck at how to get a tree from the parser.

string input="SELECT * FROM myTable";
ITokenSource lexer = new PlSqlLexer(new AntlrInputStream(input));
ITokenStream tokens = new CommonTokenStream(lexer);

var parser = new PlSqlParser(tokens, writerOutput, writerError);
parser.AddErrorListener(new ThrowExceptionErrorListener());
parser.BuildParseTree = true;
myTree = parser.# what method here #();

I saw that I can use the sql_statement() method sometime, sql_create_table() all depending on what is inside the SQL source. But how am I supposed to know what type is the content before I parsed it ? I was expecting a generic method that create objects in a tree structure so I can later feed it to MyVisitor class and generate my objects. If I don't use the right method I got a tree of typeless objects that my visitor can't handle.

What am I doing wrong ?

Edit : I'm using this grammar

When I use sql_script() I got this untyped object (I can't see the type in the popup label)

The input is this:

string input = @"
CREATE TABLE ot.persons(
    person_id NUMBER GENERATED BY DEFAULT AS IDENTITY,
    first_name VARCHAR2(50) NOT NULL,
    last_name VARCHAR2(50) NOT NULL,
    PRIMARY KEY(person_id)
);
";

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