sql.js.js

const initSqlJs = require('sql.js');

const init = initSqlJs({})

class WasmSqlite {
  constructor(/*database*/) {
    // TODO: load / store database file contents
    this.ready = init
      .then(SQL => {
        this.db = new SQL.Database()
        // polyfill for missing or mismatched default sqlite3 math functions
        this.db.create_function('ln', x => Math.log(x))
        this.db.create_function('log', (x) => Math.log10(x))
        this.db.create_function('log', (x, y) => Math.log(y) / Math.log(x))
        this.db.create_function('mod', (x, y) => x % y)
      })

    this.memory = true
    this.gc = new FinalizationRegistry(stmt => { stmt.free() })
  }

  prepare(sql) {
    const stmt = this.db.prepare(sql)
    const ret = {
      run(params) {
        try {
          stmt.bind(params)
          stmt.step()
          return { changes: stmt.db.getRowsModified(stmt) }
        } catch (err) {
          if (err.message.indexOf('NOT NULL constraint failed:') === 0) {
            err.code = 'SQLITE_CONSTRAINT_NOTNULL'
          }
          throw err
        }
      },
      get(params) {
        const columns = stmt.getColumnNames()
        stmt.bind(params)
        stmt.step()
        const row = stmt.get()
        const ret = {}
        for (let i = 0; i < columns.length; i++) {
          ret[columns[i]] = row[i]
        }
        return ret
      },
      all(params) {
        const columns = stmt.getColumnNames()
        const ret = []
        stmt.bind(params)
        while (stmt.step()) {
          const row = stmt.get()
          const obj = {}
          for (let i = 0; i < columns.length; i++) {
            obj[columns[i]] = row[i]
          }
          ret.push(obj)
        }
        return ret
      },
      *iterate(params) {
        stmt.bind(params)
        while (stmt.step()) {
          yield stmt.get()
        }
      }
    }
    this.gc.register(ret, stmt)
    return ret
  }

  exec(sql) {
    try {
      const { columns, values } = this.db.exec(sql)
      return !Array.isArray(values) ? values : values.map(val => {
        const ret = {}
        for (let i = 0; i < columns.length; i++) {
          ret[columns[i]] = val[i]
        }
        return ret
      })
    } catch (err) {
      // REVISIT: address transaction errors
      if (sql === 'BEGIN' || sql === 'ROLLBACK') { return }
      throw err
    }
  }

  function(name, config, func) {
    this.db.create_function(name, func || config)
  }

  close() { this.db.close() }
}

module.exports = WasmSqlite