Function expand_str_to_string 

pub fn expand_str_to_string(spec: &str) -> Result<String, CodegenError>

Parse, validate, emit, and pretty-print the Rust code for a DSL string.

This is convenient when you want stable, human-readable source for inspection or to write to disk with expand_str_to_file.

Parameters

• spec: The graph DSL as a UTF-8 string. It must contain exactly one graph definition.

Returns

• Ok(String): Formatted Rust source for the generated graph.
• Err(CodegenError): If parsing, validation, emission, or pretty-printing fails.

Errors

Returns:

• CodegenError::Parse or CodegenError::Validate as above.
• CodegenError::Pretty if formatting the generated tokens as a Rust file fails.