A method for compiling a mapping between a source schema and a target schema is provided. The method comprises multiple passes, including determining source node dependencies, matching hierarchy, and generating code. The method may further comprise initializing node dependency memory prior to determining source node dependencies, and freeing node dependency memory after code generation. The compiler algorithm provides for compiling user-defined functions in the mapping into the compiled representation. Another aspect of the invention provides for generating an XSL code representation of the mapping. An XSL style sheet representation may thus be generated from a visual mapping in accordance with the invention.