writeonce/prototypes/wo-db

wo-db — .wo language prototype (C++)

Phase 2 milestone 1 from docs/runtime/database.md: parser + analyzer + in-memory executor, single-user, no durability.

Implements a cut-down .wo dialect spanning all three paradigms described in 02-wo-language.md: relational, document, and graph — all in one grammar, one process, one in-RAM store.

Build & run

make                    # builds build/wo-db
make test               # runs tests/smoke.wo + tests/checkout.wo
./build/wo-db           # interactive REPL
./build/wo-db < file.wo # batch mode

Requires g++ with C++20 (tested on 13.3). No external dependencies.

Supported grammar

Schema

##sql
#users
    id int
    name string
    email string

##doc
#article_meta
    id int
    title string

##graph
#recommendations
    (user)-[:PURCHASED]->(product)

Paradigms: sql, doc, graph. Types are parsed but not enforced (prototype). Graph schema blocks are documentation only — nodes and edges are created at runtime by CREATE.

Queries

-- relational
INSERT INTO users (id, name) VALUES (1, 'Alice');
SELECT id, name FROM users WHERE id > 1 AND name != 'Carol';
UPDATE users SET email = 'a@b.com' WHERE id = 1;
DELETE FROM users WHERE id = 3;

-- document (same syntax as sql; dotted columns write nested objects)
INSERT INTO article_meta (id, title) VALUES (100, 'Intro');
SELECT title FROM article_meta;

-- graph
CREATE (u:user {id: 1, name: 'Alice'});
CREATE (u:user {id: 1})-[:PURCHASED {qty: 2}]->(p:product {id: 10});
MATCH (u:user {id: 1})-[:PURCHASED]->(p:product) RETURN u, p;

Fixed-glue: parameters, RETURNING, transactions, LIVE

The five things from the two-layer design (docs/runtime/database/02-wo-language.md) that tie the three grammars together:

-- $name parameters work everywhere (SQL, Cypher, expressions)
INSERT INTO users (email) VALUES ('a@b.com') RETURNING id AS uid;
SELECT * FROM users WHERE id = $uid;

-- cross-paradigm RETURNING threads ids from SQL into Cypher
BEGIN SNAPSHOT;
  INSERT INTO orders (user_id, status) VALUES ($uid, 'pending') RETURNING id AS oid;
  CREATE (u:user {id: $uid})-[:PURCHASED {order_id: $oid}]->(p:product {id: $pid});
COMMIT;

-- SAVEPOINT / ROLLBACK TO are parsed but not yet enforced in the prototype
BEGIN;
  SAVEPOINT s1;
  INSERT INTO users (email) VALUES ('typo@example.com');
  ROLLBACK TO s1;
COMMIT;

-- LIVE prefix reserved — inner query runs now, subscription activation in Phase 3
LIVE SELECT id, email FROM users;
LIVE MATCH (u:user)-[:PURCHASED]->(p:product) RETURN u, p;

Auto-populated id columns: when a table declares an id int column and INSERT omits it, the engine mints a fresh id from a per-table counter and fills it in. Combined with RETURNING id AS alias, this is how ids thread from SQL into Cypher inside a transaction without LAST_INSERT_ID().

Expressions

Literals (int, string, true/false/null, [array], {object}), dotted paths (meta.title), comparisons (= != < <= > >=), boolean (AND OR NOT).

REPL meta-commands

.tables     list sql/doc tables
.schema     dump schema
.exit

What's intentionally missing

This is a Phase 2 prototype, not a database. It does not implement:

• real transactions — BEGIN/COMMIT/SAVEPOINT/ROLLBACK parse and are acknowledged, but no atomic rollback, no MVCC, no WAL
• real LIVE subscriptions — the inner query runs; no delta frames, no push (Phase 3/4)
• durability, crash recovery (Phase 3)
• real document operations (array push/splice, deep path updates beyond simple dotted SET)
• joins, aggregations, subqueries
• the LSM document engine, B+ tree relational pages, native graph adjacency (Phase 3)
• wire protocol, auth (Phase 4+)

See docs/runtime/database.md for the full phase plan and docs/runtime/database/02-wo-language.md for the target language spec.

Source layout

src/
  value.hpp     tagged Value (null/bool/int/string/array/object)
  lexer.{hpp,cpp}   tokenizer
  ast.hpp       AST node types
  parser.{hpp,cpp}  recursive-descent parser
  storage.{hpp,cpp} in-memory Database (sql tables + doc tables + graph)
  executor.{hpp,cpp} walks AST, returns ResultSet
  main.cpp      REPL + batch driver
tests/
  smoke.wo      core statement coverage
  checkout.wo   cross-paradigm RETURNING + BEGIN/SAVEPOINT/COMMIT + LIVE

Roughly 1.1k lines of C++ in the wo namespace.