dt-sql-parser-semantic-analyse-plugin

A dt-sql-parser plugin with semantic result. Theory(zh-CN).

Installation

``
npm install dt-sql-parser-semantic-analyse-plugin
`

Quick Usage


`typescript
import { PostgreSQL } from 'dt-sql-parser'
import { PostgreSqlParser } from 'dt-sql-parser/dist/lib/postgresql/PostgreSqlParser'

const myPlugin = new DtSqlParserSemAnalysePlugin({
parse: {
sql: new PostgreSQL(),
parser: PostgreSqlParser,
alias: {
selectstmt: 'selectStatement',
},
stmts: [
'selectstmt',
],
entities: [
'target_el',
],
rules: {
select_target: [
PostgreSqlParser.RULE_selectstmt,
PostgreSqlParser.RULE_target_el,
]
}
}
})

const sql = 'SELECT a| FROM t'
const caretColumn = sql.indexOf('|') + 1
const result = myPlugin.parse(sql.replace('|', ''), { lineNumber: 1, columnNumber: caretColumn })
console.log(result)
`

This will use a postgresql Parser. You can get select_target text from parse result.

Notice: A rule must start with a/an statement/entity and stop with an entity. You should add a node keywords(keyword is in your parser with format: RULE_[keyword]) into stmts/entities before using it.

Add a preprocessor

`typescript
const myPlugin = new DtSqlParserSemAnalysePlugin({
preprocessor: [
(sql) => sql.toUpperCase(),
...
],
parse: {
...
}
})
`

Rule Chain Operator

You can set a negative number whose abs equals to a ruleIndex. That means exclude this rule.

Example:

`typescript
select_target_alias: [
PostgreSqlParser.RULE_target_el,
-PostgreSqlParser.RULE_attr_name,
PostgreSqlParser.RULE_collabel
]
`

🚧 I will later work on Operator.AND and Operator.OR.

Alias

Some node names in dt-sql-parser's code are different from their antlr4's definition. You should declare them in alias params.

Example:

`typescript
const myPlugin = new DtSqlParserSemAnalysePlugin({
parse: {
...
alias: {
selectstmt: 'selectStatement',
target_el: 'target_label',
table_name: 'tableName',
...
}
...
}
})
`

You can find possible alias in https://github.com/DTStack/dt-sql-parser/blob/main/src/grammar/postgresql/PostgreSqlParser.g4, then add it into alias option.

!alt text

Custom dt-sql-parser

If you want to use your custom dt-sql-parser, with external grammar(such as DISTRIBUTED, etc.), follow steps below:
1. fork dt-sql-parser.
2. change its ANTLR4 file as whatever you want.
3. build asn publish your dt-sql-parser npm package(npm run antlr4 && npm publish). Suppose to be my-dt-sql-parser.
4. use my-dt-sql-parser instead of dt-sql-parser to provide parse.sql and parse.parser.

Example:

`typescript
import { PostgreSQL } from 'my-dt-sql-parser'
import { PostgreSqlParser } from 'my-dt-sql-parser/dist/lib/postgresql/PostgreSqlParser'
const myPlugin = new DtSqlParserSemAnalysePlugin({
parse: {
sql: new PostgreSQL(),
parser: PostgreSqlParser,
...
}
})
``