Identifier

The Identifier token in RCParsing matches sequences of characters that form identifiers, such as variable names or function names, with customizable start and continue predicates.

Overview

The Identifier token matches a sequence starting with a character that satisfies a start predicate, followed by zero or more characters that satisfy a continue predicate. It supports ASCII and Unicode identifiers by default and allows custom predicates for flexibility.

Example

Here’s an example of matching a standard ASCII identifier:

var builder = new ParserBuilder();

builder.CreateToken("identifier")
    .Identifier();

var parser = builder.Build();
var result = parser.MatchToken("identifier", "variable_123");

With custom predicates:

builder.CreateToken("custom_identifier")
    .Identifier(
        start => char.IsLetter(start),
        cont => char.IsLetterOrDigit(cont) || cont == '-',
        minLength: 2
    );

var parser = builder.Build();
var result = parser.MatchToken("custom_identifier", "ab-12");

Use Cases

• Variable Names: Parse identifiers in programming languages.
• Custom Identifiers: Match domain-specific identifiers with custom rules.
• Standard Identifiers: Use default ASCII or Unicode identifier rules.

Intermediate Values

The Identifier token does not produce an intermediate value unless wrapped with a combinator:

builder.CreateToken("identifier")
    .CaptureText(b => b.Identifier());

var parser = builder.Build();
var result = parser.MatchToken("identifier", "variable");
var value = result.GetIntermediateValue<string>(); // "variable"

Notes

• Default Predicates: ASCII ([a-zA-Z_][a-zA-Z0-9_]*) or Unicode (char.IsLetter for start, char.IsLetterOrDigit or _ for continue).
• Minimum Length: Must be at least 1; use minLength for custom constraints.

Related Tutorials

• Character Token
• RepeatCharacters Token
• Keyword Token