{@End}

End-of-String Anchor

Description: A structural anchor directive that restricts a pattern match to the very end of the source text.

The {@End} directive is used within a uCalc::Transformer to ensure that a specific pattern only succeeds if it is found at the absolute conclusion of the input string. Like {@Beginning}, it is a zero-width anchor; it doesn't "consume" tokens, but validates that no more tokens remain in the stream following the match.

Positional Logic

{@End} is essential for tasks that require document-level integrity. It is commonly used to:

• Append footers or closing tags.

• Validate that a file ends with a required delimiter (like a semicolon or closing brace).

• Trigger a final "clean-up" calculation using {@@Eval} or {@Doc}.

• Comparison to Regex: {@End} is functionally equivalent to the $ anchor in standard Regular Expressions.

• Token Awareness: In a token-based engine, {@End} ensures that the preceding pattern accounts for the final token in the stream before the end-of-file (EOF) state is reached.

Examples

1. Succinct (Quick Start: EOF Identification)

Matching a specific keyword only if it is the very last thing in the document.

New(uCalc::Transformer, t)// Match 'DONE' only if it's at the very endt.FromTo("DONE {@End}", "[FINISH]")wl(t.Transform("Processing... DONE"))wl(t.Transform("DONE - continuing..."))

[Expected Output]Processing... [FINISH]DONE - continuing... (No change, since 'DONE' was not at the end)

2. Practical (Real World: Automatic Document Footer)

Using {@End} to identify the last word of a document and automatically appending a generated timestamp or signature.

New(uCalc::Transformer, t)// Match the last word and append a footert.FromTo("{@Alpha:last} {@End}", "{last}\n--- End of Report ---")var(string, doc) = "Final summary text"wl(t.Transform(doc))

[Expected Output]

Final summary text--- End of Report ---

3. Internal Test (Boundary Integrity)

Verifying that {@End} handles various token types at the boundary correctly.

New(uCalc::Transformer, t)t.FromTo("{@End}", " [EOF]")wl(t.Transform("12345"))

[Expected Output]12345 [EOF]

Strategy & Critique

• Logical Symmetry: {@End} provides the necessary symmetry to {@Beginning}, allowing developers to define rules for both boundaries of a document.
• Performance: Just like its counterpart, {@End} allows for fast-fail logic. If a pattern contains {@End} but the current token is not the last one, the engine can move on immediately.
• Naming: Consistent with {@Beginning}.
• Critique: In many programming languages, a "newline" often follows the last meaningful character. Depending on engine settings, you may need to decide if your pattern matches before or after a final {@Newline}.
• See Also: Refer to Topic 777 ({@Beginning}) for anchoring to the start of the source string.