TLang.StringBuilder

TLang.StringBuilder provides efficient string accumulation. Use it instead of repeated + concatenation in loops — plain concatenation is O(n²) when building large strings; StringBuilder is O(n).

    use TLang.StringBuilder

API

StringBuilder.create returns a new empty builder.

      let sb = StringBuilder.create()

StringBuilder.new is an alias for create.

      let sb = StringBuilder.new()

StringBuilder.append adds a string to the builder and returns the updated builder. Reassign to the same name — the builder is mutable by reference.

      let sb = StringBuilder.append(sb, "Hello, ")
      let sb = StringBuilder.append(sb, "World!")

StringBuilder.build finalises and returns the accumulated string.

      let result = StringBuilder.build(sb)    // "Hello, World!"

When to Use It

Replace this:

      let result = ""
      for (line in lines) {
          let result = result + line + "\n"   // O(n²) — avoid for large lists
      }

With this:

      let sb = StringBuilder.create()
      for (line in lines) {
          let sb = StringBuilder.append(sb, line + "\n")
      }
      let result = StringBuilder.build(sb)    // O(n)

Example — Generate a SQL Script

      use TLang.StringBuilder
      use TLang.Generator
      use TLang.File

      cmd [sql] createTable(table: String, cols: String) {
          CREATE-TABLE-IF(table: $${table}, cols: $${cols})
      }

      func main(): String {
          let tables = List.of(
              Map.of("table", "users",    "cols", "id BIGSERIAL PRIMARY KEY, name TEXT"),
              Map.of("table", "products", "cols", "id BIGSERIAL PRIMARY KEY, name TEXT, price NUMERIC")
          )

          let sb = StringBuilder.create()
          for (t in tables) {
              let sql = Generator.generate(createTable(Map.get(t, "table"), Map.get(t, "cols")))
              let sb  = StringBuilder.append(sb, sql)
          }

          let script = StringBuilder.build(sb)
          File.write("db/schema.sql", script, true)
          return "done"
      }