From 27685bc7993425e2ca02cf9497b648b9d9a2a453 Mon Sep 17 00:00:00 2001
From: Timothy Flynn <trflynn89@pm.me>
Date: Fri, 23 Apr 2021 12:39:44 -0400
Subject: [PATCH] LibSQL: Add Parser::parse_schema_and_table_name helper

Another common semantic is parsing an identifier of the form
"schema_name.table_name" / "table_name". Add a helper to do this work.

This helper does not parse any optional alias after the table name.
some syntaxes specify an alias using the AS keyword, some let the AS
keyword be optional, and others just parse it as an identifier. So
callers to this helper will just continue parsing the alias however
they require.
---
 Userland/Libraries/LibSQL/Parser.cpp | 57 +++++++++-------------------
 Userland/Libraries/LibSQL/Parser.h   |  1 +
 2 files changed, 18 insertions(+), 40 deletions(-)

diff --git a/Userland/Libraries/LibSQL/Parser.cpp b/Userland/Libraries/LibSQL/Parser.cpp
index 7752a62e6a..4e8e813eb6 100644
--- a/Userland/Libraries/LibSQL/Parser.cpp
+++ b/Userland/Libraries/LibSQL/Parser.cpp
@@ -72,16 +72,9 @@ NonnullRefPtr<CreateTable> Parser::parse_create_table_statement()
         is_error_if_table_exists = false;
     }
 
-    String schema_or_table_name = consume(TokenType::Identifier).value();
     String schema_name;
     String table_name;
-
-    if (consume_if(TokenType::Period)) {
-        schema_name = move(schema_or_table_name);
-        table_name = consume(TokenType::Identifier).value();
-    } else {
-        table_name = move(schema_or_table_name);
-    }
+    parse_schema_and_table_name(schema_name, table_name);
 
     // FIXME: Parse "AS select-stmt".
 
@@ -107,16 +100,9 @@ NonnullRefPtr<DropTable> Parser::parse_drop_table_statement()
         is_error_if_table_does_not_exist = false;
     }
 
-    String schema_or_table_name = consume(TokenType::Identifier).value();
     String schema_name;
     String table_name;
-
-    if (consume_if(TokenType::Period)) {
-        schema_name = move(schema_or_table_name);
-        table_name = consume(TokenType::Identifier).value();
-    } else {
-        table_name = move(schema_or_table_name);
-    }
+    parse_schema_and_table_name(schema_name, table_name);
 
     consume(TokenType::SemiColon);
 
@@ -633,16 +619,9 @@ Optional<NonnullRefPtr<Expression>> Parser::parse_in_expression(NonnullRefPtr<Ex
         return create_ast_node<InChainedExpression>(move(expression), move(chain), invert_expression);
     }
 
-    String schema_or_table_name = consume(TokenType::Identifier).value();
     String schema_name;
     String table_name;
-
-    if (consume_if(TokenType::Period)) {
-        schema_name = move(schema_or_table_name);
-        table_name = consume(TokenType::Identifier).value();
-    } else {
-        table_name = move(schema_or_table_name);
-    }
+    parse_schema_and_table_name(schema_name, table_name);
 
     if (match(TokenType::ParenOpen)) {
         // FIXME: Parse "table-function".
@@ -724,16 +703,9 @@ NonnullRefPtr<CommonTableExpression> Parser::parse_common_table_expression()
 NonnullRefPtr<QualifiedTableName> Parser::parse_qualified_table_name()
 {
     // https://sqlite.org/syntax/qualified-table-name.html
-    String schema_or_table_name = consume(TokenType::Identifier).value();
     String schema_name;
     String table_name;
-
-    if (consume_if(TokenType::Period)) {
-        schema_name = move(schema_or_table_name);
-        table_name = consume(TokenType::Identifier).value();
-    } else {
-        table_name = move(schema_or_table_name);
-    }
+    parse_schema_and_table_name(schema_name, table_name);
 
     String alias;
     if (consume_if(TokenType::As))
@@ -803,16 +775,9 @@ NonnullRefPtr<TableOrSubquery> Parser::parse_table_or_subquery()
 {
     // https://sqlite.org/syntax/table-or-subquery.html
     if (match(TokenType::Identifier)) {
-        String schema_or_table_name = consume().value();
         String schema_name;
         String table_name;
-
-        if (consume_if(TokenType::Period)) {
-            schema_name = move(schema_or_table_name);
-            table_name = consume(TokenType::Identifier).value();
-        } else {
-            table_name = move(schema_or_table_name);
-        }
+        parse_schema_and_table_name(schema_name, table_name);
 
         String table_alias;
         if (consume_if(TokenType::As) || match(TokenType::Identifier))
@@ -859,6 +824,18 @@ NonnullRefPtr<OrderingTerm> Parser::parse_ordering_term()
     return create_ast_node<OrderingTerm>(move(expression), move(collation_name), order, nulls);
 }
 
+void Parser::parse_schema_and_table_name(String& schema_name, String& table_name)
+{
+    String schema_or_table_name = consume(TokenType::Identifier).value();
+
+    if (consume_if(TokenType::Period)) {
+        schema_name = move(schema_or_table_name);
+        table_name = consume(TokenType::Identifier).value();
+    } else {
+        table_name = move(schema_or_table_name);
+    }
+}
+
 Token Parser::consume()
 {
     auto old_token = m_parser_state.m_token;
diff --git a/Userland/Libraries/LibSQL/Parser.h b/Userland/Libraries/LibSQL/Parser.h
index 827d60c37c..6d6cf91591 100644
--- a/Userland/Libraries/LibSQL/Parser.h
+++ b/Userland/Libraries/LibSQL/Parser.h
@@ -84,6 +84,7 @@ private:
     NonnullRefPtr<ResultColumn> parse_result_column();
     NonnullRefPtr<TableOrSubquery> parse_table_or_subquery();
     NonnullRefPtr<OrderingTerm> parse_ordering_term();
+    void parse_schema_and_table_name(String& schema_name, String& table_name);
 
     template<typename ParseCallback>
     void parse_comma_separated_list(bool surrounded_by_parentheses, ParseCallback&& parse_callback)