private static StatementExpression parse(DocumentType type, ScriptParserContext parserConfig, String content) {
        try {
            parserConfig.setInputStream(new IndexingInput(content));
            return StatementExpression.newInstance(parserConfig);
        } catch (ParseException e) {
            throw new IllegalArgumentException("Illegal indexing script for " + type, e);
        }
    }
Returns an unmodifiable map from document type name to a map of the subset of indexing statements
to run for each input field which *only* depend on that field.
docprocs/src/main/java/com/yahoo/docprocs/indexing/ScriptManager.java