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docs: update visitor demo and listener demo

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hayden 2023-12-19 20:51:40 +08:00
parent d4c97ef833
commit 447ab7f331
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67
README-zh_CN.md
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@ -156,27 +156,38 @@ console.log(tokens)
使用 Visitor 模式访问 AST 中的指定节点 使用 Visitor 模式访问 AST 中的指定节点
```javascript ```typescript
import { MySQL, MySqlParserVisitor } from 'dt-sql-parser'; import { MySQL, AbstractParseTreeVisitor } from 'dt-sql-parser';
import type { MySqlParserVisitor } from 'dt-sql-parser';
const parser = new MySQL() const parser = new MySQL();
const sql = `select id,name from user1;` const sql = `select id,name from user1;`;
// parseTree const tree = parser.parse(sql);
const tree = parser.parse(sql)
class MyVisitor extends MySqlParserVisitor { type Result = string;
// 重写 visitTableName 方法
class MyVisitor extends AbstractParseTreeVisitor<Result> implements MySqlParserVisitor<Result> {
protected defaultResult() {
return '';
}
visitTableName(ctx) { visitTableName(ctx) {
let tableName = ctx.getText().toLowerCase() let tableName = ctx.text.toLowerCase();
console.log('TableName', tableName) console.log('TableName', tableName);
return '';
} }
// 重写 visitSelectElements 方法
visitSelectElements(ctx) { visitSelectElements(ctx) {
let selectElements = ctx.getText().toLowerCase() let selectElements = ctx.text.toLowerCase();
console.log('SelectElements', selectElements) console.log('SelectElements', selectElements);
return '';
}
visitProgram(ctx) {
return 'Return by program node'
} }
} }
const visitor = new MyVisitor() const visitor = new MyVisitor();
visitor.visit(tree) const result = visitor.visit(tree);
console.log(result);
``` ```
*输出：* *输出：*
@ -186,6 +197,9 @@ visitor.visit(tree)
SelectElements id,name SelectElements id,name
TableName user1 TableName user1
*/ */
/*
Return by program node
*/
``` ```
> 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 > 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
@ -194,25 +208,26 @@ TableName user1
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。 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。
```javascript ```typescript
import { MySQL, MySqlParserListener } from 'dt-sql-parser'; import { MySQL } from 'dt-sql-parser';
import type { MySqlParserListener } from 'dt-sql-parser';
const parser = new MySQL(); const parser = new MySQL();
const sql = 'select id,name from user1;' const sql = 'select id,name from user1;';
// parseTree const parseTree = parser.parse(sql);
const tree = parser.parse(sql)
class MyListener extends MySqlParserListener { class MyListener implements MySqlParserListener {
enterTableName(ctx) { enterTableName(ctx) {
let tableName = ctx.getText().toLowerCase() let tableName = ctx.text.toLowerCase();
console.log('TableName', tableName) console.log('TableName:', tableName);
} }
enterSelectElements(ctx) { enterSelectElements(ctx) {
let selectElements = ctx.getText().toLowerCase() let selectElements = ctx.text.toLowerCase();
log('SelectElements', selectElements) console.log('SelectElements:', selectElements);
} }
} }
const listenTableName = new MyListener(); const listenTableName = new MyListener();
parser.listen(listenTableName, tree); parser.listen(listenTableName as MySqlParserListener, parseTree);
``` ```
*输出：* *输出：*

76
README.md
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@ -163,35 +163,49 @@ console.log(tokens)
Traverse the tree node by the Visitor: Traverse the tree node by the Visitor:
```javascript ```typescript
import { MySQL, MySqlParserVisitor } from 'dt-sql-parser'; import { MySQL, AbstractParseTreeVisitor } from 'dt-sql-parser';
import type { MySqlParserVisitor } from 'dt-sql-parser';
const parser = new MySQL() const parser = new MySQL();
const sql = `select id,name from user1;` const sql = `select id,name from user1;`;
// parseTree const tree = parser.parse(sql);
const tree = parser.parse(sql)
class MyVisitor extends MySqlParserVisitor { type Result = string;
// overwrite visitTableName
class MyVisitor extends AbstractParseTreeVisitor<Result> implements MySqlParserVisitor<Result> {
protected defaultResult() {
return '';
}
visitTableName(ctx) { visitTableName(ctx) {
let tableName = ctx.getText().toLowerCase() let tableName = ctx.text.toLowerCase();
console.log('TableName', tableName) console.log('TableName:', tableName);
return '';
} }
// overwrite visitSelectElements
visitSelectElements(ctx) { visitSelectElements(ctx) {
let selectElements = ctx.getText().toLowerCase() let selectElements = ctx.text.toLowerCase();
console.log('SelectElements', selectElements) console.log('SelectElements:', selectElements);
return '';
}
visitProgram(ctx) {
return 'Return by program node'
} }
} }
const visitor = new MyVisitor() const visitor = new MyVisitor();
visitor.visit(tree) const result = visitor.visit(tree);
console.log(result);
``` ```
*output:* *output:*
```javascript ```javascript
/* /*
SelectElements id,name SelectElements: id,name
TableName user1 TableName: user1
*/
/*
Return by program node
*/ */
``` ```
@ -201,34 +215,34 @@ TableName user1
Access the specified node in the AST by the Listener Access the specified node in the AST by the Listener
```javascript ```typescript
import { MySQL, MySqlParserListener } from 'dt-sql-parser'; import { MySQL } from 'dt-sql-parser';
import type { MySqlParserListener } from 'dt-sql-parser';
const parser = new MySQL(); const parser = new MySQL();
const sql = 'select id,name from user1;' const sql = 'select id,name from user1;';
// parseTree const parseTree = parser.parse(sql);
const tree = parser.parse(sql)
class MyListener extends MySqlParserListener { class MyListener implements MySqlParserListener {
enterTableName(ctx) { enterTableName(ctx) {
let tableName = ctx.getText().toLowerCase() let tableName = ctx.text.toLowerCase();
console.log('TableName', tableName) console.log('TableName:', tableName);
} }
enterSelectElements(ctx) { enterSelectElements(ctx) {
let selectElements = ctx.getText().toLowerCase() let selectElements = ctx.text.toLowerCase();
console.log('SelectElements', selectElements) console.log('SelectElements:', selectElements);
} }
} }
const listenTableName = new MyListener(); const listenTableName = new MyListener();
parser.listen(listenTableName, tree); parser.listen(listenTableName as MySqlParserListener, parseTree);
``` ```
*output:* *output:*
```javascript ```javascript
/* /*
SelectElements id,name SelectElements: id,name
TableName user1 TableName: user1
*/ */
``` ```