docs: update visitor demo and listener demo
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hayden
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@ -156,27 +156,38 @@ console.log(tokens)
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使用 Visitor 模式访问 AST 中的指定节点
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```javascript
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import { MySQL, MySqlParserVisitor } from 'dt-sql-parser';
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```typescript
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import { MySQL, AbstractParseTreeVisitor } from 'dt-sql-parser';
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import type { MySqlParserVisitor } from 'dt-sql-parser';
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const parser = new MySQL()
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const sql = `select id,name from user1;`
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// parseTree
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const tree = parser.parse(sql)
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class MyVisitor extends MySqlParserVisitor {
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// 重写 visitTableName 方法
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const parser = new MySQL();
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const sql = `select id,name from user1;`;
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const tree = parser.parse(sql);
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type Result = string;
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class MyVisitor extends AbstractParseTreeVisitor<Result> implements MySqlParserVisitor<Result> {
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protected defaultResult() {
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return '';
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}
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visitTableName(ctx) {
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let tableName = ctx.getText().toLowerCase()
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console.log('TableName', tableName)
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let tableName = ctx.text.toLowerCase();
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console.log('TableName', tableName);
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return '';
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}
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// 重写 visitSelectElements 方法
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visitSelectElements(ctx) {
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let selectElements = ctx.getText().toLowerCase()
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console.log('SelectElements', selectElements)
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let selectElements = ctx.text.toLowerCase();
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console.log('SelectElements', selectElements);
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return '';
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}
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visitProgram(ctx) {
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return 'Return by program node'
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}
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}
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const visitor = new MyVisitor()
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visitor.visit(tree)
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const visitor = new MyVisitor();
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const result = visitor.visit(tree);
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console.log(result);
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```
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*输出：*
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@ -186,6 +197,9 @@ visitor.visit(tree)
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SelectElements id,name
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TableName user1
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*/
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/*
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Return by program node
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*/
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```
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> 提示：使用 Visitor 模式时，节点的方法名称可以在对应 SQL 目录下的 Visitor 文件中查找
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@ -194,25 +208,26 @@ TableName user1
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Listener 模式，利用 [ANTLR4](https://github.com/antlr/antlr4) 提供的 `ParseTreeWalker` 对象遍历 AST，进入各个节点时调用对应的方法。
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```javascript
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import { MySQL, MySqlParserListener } from 'dt-sql-parser';
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```typescript
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import { MySQL } from 'dt-sql-parser';
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import type { MySqlParserListener } from 'dt-sql-parser';
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const parser = new MySQL();
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const sql = 'select id,name from user1;'
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// parseTree
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const tree = parser.parse(sql)
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class MyListener extends MySqlParserListener {
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const sql = 'select id,name from user1;';
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const parseTree = parser.parse(sql);
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class MyListener implements MySqlParserListener {
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enterTableName(ctx) {
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let tableName = ctx.getText().toLowerCase()
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console.log('TableName', tableName)
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let tableName = ctx.text.toLowerCase();
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console.log('TableName:', tableName);
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}
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enterSelectElements(ctx) {
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let selectElements = ctx.getText().toLowerCase()
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log('SelectElements', selectElements)
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let selectElements = ctx.text.toLowerCase();
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console.log('SelectElements:', selectElements);
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}
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}
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const listenTableName = new MyListener();
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parser.listen(listenTableName, tree);
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parser.listen(listenTableName as MySqlParserListener, parseTree);
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```
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*输出：*
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76
README.md
76
README.md
@ -163,35 +163,49 @@ console.log(tokens)
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Traverse the tree node by the Visitor:
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```javascript
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import { MySQL, MySqlParserVisitor } from 'dt-sql-parser';
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```typescript
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import { MySQL, AbstractParseTreeVisitor } from 'dt-sql-parser';
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import type { MySqlParserVisitor } from 'dt-sql-parser';
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const parser = new MySQL()
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const sql = `select id,name from user1;`
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// parseTree
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const tree = parser.parse(sql)
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class MyVisitor extends MySqlParserVisitor {
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// overwrite visitTableName
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const parser = new MySQL();
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const sql = `select id,name from user1;`;
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const tree = parser.parse(sql);
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type Result = string;
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class MyVisitor extends AbstractParseTreeVisitor<Result> implements MySqlParserVisitor<Result> {
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protected defaultResult() {
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return '';
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}
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visitTableName(ctx) {
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let tableName = ctx.getText().toLowerCase()
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console.log('TableName', tableName)
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let tableName = ctx.text.toLowerCase();
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console.log('TableName:', tableName);
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return '';
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}
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// overwrite visitSelectElements
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visitSelectElements(ctx) {
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let selectElements = ctx.getText().toLowerCase()
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console.log('SelectElements', selectElements)
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let selectElements = ctx.text.toLowerCase();
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console.log('SelectElements:', selectElements);
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return '';
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}
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visitProgram(ctx) {
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return 'Return by program node'
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}
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}
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const visitor = new MyVisitor()
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visitor.visit(tree)
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const visitor = new MyVisitor();
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const result = visitor.visit(tree);
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console.log(result);
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```
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*output:*
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```javascript
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/*
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SelectElements id,name
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TableName user1
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SelectElements: id,name
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TableName: user1
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*/
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/*
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Return by program node
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*/
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```
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@ -201,34 +215,34 @@ TableName user1
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Access the specified node in the AST by the Listener
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```javascript
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import { MySQL, MySqlParserListener } from 'dt-sql-parser';
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```typescript
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import { MySQL } from 'dt-sql-parser';
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import type { MySqlParserListener } from 'dt-sql-parser';
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const parser = new MySQL();
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const sql = 'select id,name from user1;'
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// parseTree
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const tree = parser.parse(sql)
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class MyListener extends MySqlParserListener {
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const sql = 'select id,name from user1;';
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const parseTree = parser.parse(sql);
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class MyListener implements MySqlParserListener {
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enterTableName(ctx) {
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let tableName = ctx.getText().toLowerCase()
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console.log('TableName', tableName)
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let tableName = ctx.text.toLowerCase();
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console.log('TableName:', tableName);
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}
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enterSelectElements(ctx) {
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let selectElements = ctx.getText().toLowerCase()
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console.log('SelectElements', selectElements)
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let selectElements = ctx.text.toLowerCase();
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console.log('SelectElements:', selectElements);
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}
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}
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const listenTableName = new MyListener();
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parser.listen(listenTableName, tree);
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parser.listen(listenTableName as MySqlParserListener, parseTree);
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```
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*output:*
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```javascript
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/*
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SelectElements id,name
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TableName user1
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SelectElements: id,name
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TableName: user1
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*/
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```
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