feat: integrate SQLGlot for SQL to Pure Relation conversion

legendql/__init__.py

@@ -16,5 +16,6 @@
 from legendql.ql import query, LegendQL
 from legendql.store import store
 from legendql.functions import aggregate, over, unbounded, rows, range, left, avg, count, sum, rank, lead, lag, row_number
+from legendql.sql_parser import sql_to_pure_relation, SQLToLegendQLConverter
 
-__all__ = ['db', 'table', 'using', 'using_db', 'using_db_def', 'query', 'LegendQL', 'store', 'aggregate', 'over', 'unbounded', 'rows', 'range', 'left', 'avg', 'count', 'sum', 'rank', 'lead', 'lag', 'row_number']
+__all__ = ['db', 'table', 'using', 'using_db', 'using_db_def', 'query', 'LegendQL', 'store', 'aggregate', 'over', 'unbounded', 'rows', 'range', 'left', 'avg', 'count', 'sum', 'rank', 'lead', 'lag', 'row_number', 'sql_to_pure_relation', 'SQLToLegendQLConverter']

legendql/sql_examples.py

@@ -0,0 +1,32 @@
+"""Examples demonstrating SQL to Pure Relation conversion using SQLGlot."""
+
+import pyarrow as pa
+from legendql.sql_parser import sql_to_pure_relation
+from legendql.model.schema import Database, Table
+from legendql.runtime.pure.db.h2 import H2DatabaseDefinition
+
+employees_table = Table(
+    table="employees",
+    columns=[
+        pa.field("id", pa.int32()),
+        pa.field("name", pa.utf8()),
+        pa.field("department", pa.utf8()),
+        pa.field("salary", pa.float32())
+    ]
+)
+
+database = Database(name="company", children=[employees_table])
+db_def = H2DatabaseDefinition(sqls=[])
+
+sql1 = "SELECT id, name FROM employees"
+pure_code1 = sql_to_pure_relation(sql1, db_def, database)
+print("Example 1:")
+print(f"SQL: {sql1}")
+print(f"Pure Relation: {pure_code1}")
+print()
+
+sql2 = "SELECT name, department, salary FROM employees"
+pure_code2 = sql_to_pure_relation(sql2, db_def, database)
+print("Example 2:")
+print(f"SQL: {sql2}")
+print(f"Pure Relation: {pure_code2}")

legendql/sql_parser.py

@@ -0,0 +1,104 @@
+# Copyright 2025 Goldman Sachs
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+from typing import List, Optional
+import sqlglot
+from sqlglot import exp, parse_one
+
+from legendql.model.metamodel import (
+    SelectionClause, DatabaseFromClause, ColumnReferenceExpression, 
+    Expression, Clause
+)
+from legendql.model.schema import Database, Table, Schema
+from legendql.query import Query
+from legendql.runtime.pure.db.type import DatabaseDefinition
+
+
+class SQLToLegendQLConverter:
+    """Converts SQL statements to LegendQL metamodel using SQLGlot parsing."""
+
+    def __init__(self, database_definition: DatabaseDefinition, database: Database):
+        self.database_definition = database_definition
+        self.database = database
+
+    def parse_sql_to_query(self, sql: str) -> Query:
+        """Parse SQL string and convert to LegendQL Query object."""
+        try:
+            parsed = parse_one(sql)
+            if not isinstance(parsed, exp.Select):
+                raise ValueError(f"Only SELECT statements are currently supported, got: {type(parsed)}")
+
+            return self._convert_select_to_query(parsed)
+        except Exception as e:
+            raise ValueError(f"Failed to parse SQL: {sql}. Error: {str(e)}")
+
+    def _convert_select_to_query(self, select_ast: exp.Select) -> Query:
+        """Convert SQLGlot Select AST to LegendQL Query."""
+        table_info = self._extract_table_info(select_ast)
+
+        query = Query.from_table(
+            self.database_definition, 
+            self.database, 
+            table_info['table_name']
+        )
+
+        if select_ast.expressions:
+            selection_expressions = []
+            for expr in select_ast.expressions:
+                legend_expr = self._convert_expression(expr)
+                selection_expressions.append(legend_expr)
+
+            query._clauses = [query._clauses[0]]  # Keep the FROM clause
+            query._add_clause(SelectionClause(selection_expressions))
+
+        return query
+
+    def _extract_table_info(self, select_ast: exp.Select) -> dict:
+        """Extract table name and schema information from SELECT AST."""
+        table_node = select_ast.find(exp.Table)
+        if not table_node:
+            raise ValueError("No table found in SELECT statement")
+
+        return {
+            'table_name': table_node.name,
+            'schema_name': table_node.db if hasattr(table_node, 'db') else None,
+            'database_name': table_node.catalog if hasattr(table_node, 'catalog') else None
+        }
+
+    def _convert_expression(self, expr: exp.Expression) -> Expression:
+        """Convert SQLGlot expression to LegendQL Expression."""
+        if isinstance(expr, exp.Column):
+            return ColumnReferenceExpression(expr.name)
+        elif isinstance(expr, exp.Star):
+            raise NotImplementedError("SELECT * is not yet implemented")
+        else:
+            return ColumnReferenceExpression(str(expr))
+
+
+def sql_to_pure_relation(sql: str, database_definition: DatabaseDefinition, database: Database) -> str:
+    """
+    Convert SQL statement to Pure Relation code.
+
+    Args:
+        sql: SQL statement to convert
+        database_definition: Database definition for execution
+        database: Database schema information
+
+    Returns:
+        Pure Relation code string
+    """
+    converter = SQLToLegendQLConverter(database_definition, database)
+    query = converter.parse_sql_to_query(sql)
+    return query.to_string()

pyproject.toml

@@ -24,6 +24,7 @@ numpy = [
     { version = ">=1.20.0", python = "<3.12" },
     { version = ">=1.26.0", python = ">=3.12" }
 ]
+sqlglot = ">=26.0.0"
 
 
 [tool.poetry.group.dev.dependencies]

test_sql_integration.py

@@ -0,0 +1,40 @@
+#!/usr/bin/env python3
+"""Test script for SQLGlot integration with LegendQL."""
+
+import pyarrow as pa
+from legendql.sql_parser import sql_to_pure_relation
+from legendql.model.schema import Database, Table
+from legendql.runtime.pure.db.h2 import H2DatabaseDefinition
+
+def test_basic_sql_conversion():
+    """Test basic SQL SELECT conversion to Pure Relation code."""
+
+    table = Table(
+        table="tableC",
+        columns=[
+            pa.field("colA", pa.utf8()),
+            pa.field("colB", pa.int32())
+        ]
+    )
+    database = Database(name="testdb", children=[table])
+
+    db_def = H2DatabaseDefinition(sqls=[])
+
+    sql = "SELECT colA, colB FROM tableC"
+
+    try:
+        pure_relation_code = sql_to_pure_relation(sql, db_def, database)
+        print("SQL:", sql)
+        print("Pure Relation Code:", pure_relation_code)
+        print("✅ Basic SQL conversion successful!")
+        return True
+    except Exception as e:
+        print(f"❌ Error converting SQL: {e}")
+        return False
+
+if __name__ == "__main__":
+    success = test_basic_sql_conversion()
+    if success:
+        print("\n🎉 SQLGlot integration test passed!")
+    else:
+        print("\n💥 SQLGlot integration test failed!")