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Token System Guide

This guide explains how internal tokens like token are structured, parsed, validated, and consumed by query builders.

All tokens (e.g., token, Table, Condition) embed BaseToken, making them both Errorable (via GetError/IsErrored/SetError) and Kindable (via GetKind/SetKind). All these methods are nil‐safe: calling any of them on a nil token will not panic and returns a safe default (e.g., IsErrored() → false, GetKind() → UnknownKind).

📜 Principles

  • Tokens are internal, immutable, and self‐validating.
  • Each token may carry an Error (via the Errorable contract).
    • Calling IsErrored() on a token with no error (or on a nil token) returns false.
    • Calling GetError() on a token with no error (or on a nil token) returns nil.
  • Tokens also expose a Kind (via the Kindable contract).
    • Calling GetKind() on a token with no kind set (or on a nil token) returns UnknownKind.
    • Calling SetKind(...) on a nil token is a no‐op (nil‐safe).
  • Tokens do not handle dialect quoting or full SQL rendering beyond their own RenderName() / RenderAlias().
  • BaseToken provides name, alias, error, and kind logic for all tokens, ensuring it is reusable and consistent.

🧩 Core Behaviors

  • Input normalization
  • Alias resolution
  • Error tracking
  • Dialect-safe rendering

🔍 Qualification & Validation

A generic token may become invalid under any of the following scenarios. All tokens embed BaseToken, so these apply universally (token, Table, Condition, etc.):

  • Empty input: An input string that is blank or only whitespace sets an error.
  • Comma-separated expression: Inputs containing commas (,) are rejected (aliases must not be comma-separated).
  • Starts with AS: Inputs beginning with AS or whose base resolves to AS only are invalid (missing identifier before AS).
  • Alias conflict: When both inline and explicit aliases are provided but do not match (e.g., "users.id AS uid", "other_uid"), an error is set.
  • Qualifier conflict: For tokens that parse qualifiers (e.g., users.id), if the qualifier does not match an attached context (e.g., a mismatched table alias), the token becomes invalid.
  • Reserved word misuse: If the parsed base identifier itself is a reserved word (e.g., "AS" only), the token is invalid.

All of the above conditions will cause IsErrored() to return true, with details accessible via GetError(). You can check IsValid() (equivalent to !IsErrored() && Name != "") before including a token in any generated SQL.

The following core token is the base for all SQL tokens in Entiqon:

Name Description Access
📄 BaseToken Is the abstract foundational structure used by all SQL tokens in Entiqon (such as token, Table, and Condition) Private

This modular reference allows isolated testing and future reuse for other token types.

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