LLMFunction.java

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package org.apache.doris.nereids.trees.expressions.functions.llm;

import org.apache.doris.catalog.Env;
import org.apache.doris.catalog.LLMResource;
import org.apache.doris.catalog.Resource;
import org.apache.doris.nereids.exceptions.AnalysisException;
import org.apache.doris.nereids.trees.expressions.Expression;
import org.apache.doris.nereids.trees.expressions.functions.ExplicitlyCastableSignature;
import org.apache.doris.nereids.trees.expressions.functions.PropagateNullable;
import org.apache.doris.nereids.trees.expressions.functions.scalar.ScalarFunction;
import org.apache.doris.nereids.trees.expressions.visitor.ExpressionVisitor;
import org.apache.doris.qe.ConnectContext;

import com.google.common.base.Strings;

/**
 * Base class for LLM related functions.
 */
public abstract class LLMFunction extends ScalarFunction
        implements PropagateNullable, ExplicitlyCastableSignature {
    /**
     * constructor with at least 1 argument.
     */
    public LLMFunction(String name, Expression... expressions) {
        super(name, expressions);
        if (children.isEmpty()) {
            throw new AnalysisException(name + " requires at least 1 argument.");
        }
    }

    public abstract int getMaxArgsNum();

    @Override
    public void checkLegalityAfterRewrite() {
        if (arity() == getMaxArgsNum()) {
            //The resource must be literal
            if (!child(0).isLiteral()) {
                throw new AnalysisException("LLM Function must accept literal for the resource name.");
            }

            //Check if the resource is valid
            String resourceName = getArgument(0).toString().replaceAll("^['\"]|['\"]$", "");
            Resource resource = Env.getCurrentEnv().getResourceMgr().getResource(resourceName);
            if (!(resource instanceof LLMResource)) {
                throw new AnalysisException("LLM resource '" + resourceName + "' does not exist");
            }
        }
    }

    /**
     *  If a user doesn't specify which resource to use when calling a function
     *  the current session variable will automatically allocate a resource.
     *  <p>
     *  1. First, attempt to use the user-specified argument passed to the function.
     *  2. If not available, try using the global default LLM resource.
     */
    public static String getResourceName() throws AnalysisException {
        String resourceName = ConnectContext.get().getSessionVariable().defaultLLMResource;
        if (Strings.isNullOrEmpty(resourceName)) {
            throw new AnalysisException("Please specify the LLM Resource in argument "
                    + "or session variable.");
        }
        return resourceName;
    }

    @Override
    public void checkLegalityBeforeTypeCoercion() {
        checkLegalityAfterRewrite();
    }

    @Override
    public abstract <R, C> R accept(ExpressionVisitor<R, C> visitor, C context);
}