pgsql-ast-parser - npm Package Compare versions

Comparing version 1.0.5 to 1.0.6

package.json

 {
   "name": "pgsql-ast-parser",
-  "version": "1.0.5",
-  "description": "Yet another simple Postgres SQL parser",
+  "version": "1.0.6",
+  "description": "Yet another simple Postgres SQL parser/modifier",
   "main": "index.js",
@@ -27,3 +27,6 @@ "repository": "https://github.com/oguimbal/pgsql-ast-parser",
     "pgsql",
-    "postgresql"
+    "postgresql",
+    "node",
+    "parser",
+    "ast"
   ],
@@ -30,0 +33,0 @@ "dependencies": {

readme.md

@@ -1,2 +0,2 @@
-🏃‍♀️ `pgsql-ast-parser` is a Postgres SQL syntax parser. It produces a typed AST tree, covering the most common syntaxes of pgsql.
+🏃‍♀️ `pgsql-ast-parser` is a Postgres SQL syntax parser. It produces a typed AST (Abstract Syntax Tree), covering the most common syntaxes of pgsql.
 
@@ -33,3 +33,3 @@ **⚠** This parser does not support (yet) PL/pgSQL. It might not even cover some funky syntaxes.
 
-Parse sql to an AST (Abstract Syntax Tree) like this:
+Parse sql to an AST like this:
 
@@ -52,3 +52,3 @@ ```typescript
 
-There is a helper for that: `astVisitor`.
+There is a helper for that: [astVisitor](/src/ast-visitor.ts).
 
@@ -101,9 +101,10 @@ Here is an example which lists all the tables used in a request, and which counts how many joins it contains:
 
-ℹ Like with visitor, you can also convert subparts of AST to SQL (not necessarily a whole statement) by calling other methods of toSql.
+Like with `astVisitor()` or `astModifier()`, you can also convert subparts of AST to SQL (not necessarily a whole statement) by calling other methods of toSql.
 
 
+
 # 📝 Modifying SQL AST
 
 
-There is a special kind of visitor, which I called `astMapper`, which allows you to traverse & modify ASTs on the fly.
+There is a special kind of visitor, which I called [astMapper](/src/ast-mapper.ts), which allows you to traverse & modify ASTs on the fly.
 
@@ -140,3 +141,22 @@ For instance, you could rename a table in a request like this:
 
+Good to know: If you use Typescript, return types will force  you to return something compatible with a valid AST.
 
+However, if you wish to remove a node from a tree, you can return null. For instance, this sample removes all references to column `'foo'`:
+
+```typescript
+// create a mapper
+const mapper = astMapper(map => ({
+    ref: c => c.name === 'foo' ? null : c,
+}))
+
+// process sql
+const result = mapper.statement(parseFirst('select foo, bar from test'));
+
+// Prints: SELECT "bar" FROM "test"
+console.log(toSql.statement(result!));
+```
+
+If no valid AST can be produced after having removed it, `result` will be null.
+
+
 ## A note on `astMapper` performance:
@@ -143,0 +163,0 @@

src/ast-mapper.spec.ts

@@ -172,2 +172,15 @@ import 'mocha';
 
+    it('removes node', () => {
+        // create a mapper
+        const mapper = astMapper(map => ({
+            ref: c => c.name === 'foo' ? null : c,
+        }))
+
+        // process sql
+        const result = mapper.statement(parseFirst('select foo, bar from test'));
+
+        expect(toSql.statement(result!)).to.deep.equal('SELECT "bar"  FROM "test"');
+
+    })
+
 });

No alert changes

Improved metrics

Total package byte prevSize

651722

increased by0.17%

Lines of code

7088

increased by0.13%

Number of lines in readme file

219

increased by10.05%

No dependency changes