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An S-Expression inspiried library focused on iterators.

There is a newer version: 1.1.23

package com.github.basking2.sdsai.itrex.functions;

import java.util.Iterator;

import com.github.basking2.sdsai.itrex.EvaluationContext;

/**
 * A function that fetches function help text.
 */
public class HelpFunction implements FunctionInterface, HelpfulFunction {
    
    /**
     * {@inheritDoc}
     */
    @Override
    public String apply(final Iterator args, final EvaluationContext evaluationContext) {
        
        final StringBuilder stringBuilder = new StringBuilder();
        boolean verbose = false;

        while (args.hasNext()) {
            final String functionName;
            final Object o = args.next();
            HelpfulFunction hf = null;

            if (o instanceof HelpfulFunction) {
                hf = (HelpfulFunction)o;
                functionName = o.toString();
            }
            else if (o instanceof String) {
                functionName = (String)o;
                if ("verbose".equals(functionName) || "-v".equals(functionName)) {
                    verbose = true;
                    continue;
                }
                else {
                    final FunctionInterface f = evaluationContext.getFunction(functionName);
                    if (f instanceof HelpfulFunction) {
                        hf = (HelpfulFunction)o;
                    }
                }
            }
            else {
                hf = null;
                functionName = "";
            }

            if (hf != null) {
                stringBuilder.
                    append(hf.functionHelp(functionName, verbose)).
                    append("\n");
            }
            else {
                stringBuilder.append("No help for function ").append(o.toString()).append(".\n");
            }
        }

        return stringBuilder.toString();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String functionHelp(final String name, final boolean verbose) {
        return "    [\""+name+"\", [-v], [verbose], \"function name\", [\"curry\" \"another function name\"]]\n" +
               "      -v       - Turn on verbose output, if available.\n" +
               "      version  - Turn on verbose output, if available.\n" +
               "      string   - Strings are used as names of functions to fetch help for.\n"+
               "      function - If a function object is an argument, its help data is retrieved."
               ;
    }


}