Kawa/kawa/lang/SyntaxRules.java

package kawa.lang;

import gnu.expr.*;
import gnu.kawa.format.Printable;
import gnu.kawa.format.ReportFormat;
import gnu.kawa.functions.DisplayFormat;
import gnu.kawa.io.OutPort;
import gnu.lists.*;
import gnu.mapping.*;
import gnu.text.*;
import java.io.*;

public class SyntaxRules extends Procedure1
    implements Printable, Externalizable {
    /** The list of literal identifiers as specified in the syntax-rules form.
     */
    Object[] literal_identifiers;

    SyntaxRule[] rules;

    /* The largest (num_variables+template_identifier.length) for any rule. */
    int maxVars = 0;

    public SyntaxRules() {
    }

    /** The compiler generates calls to this constructor. */
    public SyntaxRules(Object[] literal_identifiers, SyntaxRule[] rules,
                       int maxVars, Object name) {
        this.literal_identifiers = literal_identifiers;
        this.rules = rules;
        this.maxVars = maxVars;
        if (name != null)
            this.setSymbol(name);
    }

    public SyntaxRules(Object ellipsis, Object[] literal_identifiers,
                       Object srules, Translator tr) {
        Macro curMacro = tr.currentMacroDefinition;
        if (curMacro != null) {
            Object curName = curMacro.getSymbol();
            if (curName != null)
                this.setSymbol(curName);
        }
        this.literal_identifiers = literal_identifiers;
        int rules_count = Translator.listLength(srules);
        if (rules_count < 0) {
            rules_count = 0;
            tr.syntaxError ("missing or invalid syntax-rules");
        }
        this.rules = new SyntaxRule [rules_count];
        Pair rules_pair;
        // SyntaxForm, if any, wrapping rest of rules list.
        SyntaxForm rules_syntax = null;
        for (int i = 0;  i < rules_count;  i++, srules = rules_pair.getCdr()) {
            while (srules instanceof SyntaxForm) {
                rules_syntax = (SyntaxForm) srules;
                srules = rules_syntax.getDatum();
            }
            rules_pair = (Pair) srules;

            // SyntaxForm, if any, wrapping the current rule.
            SyntaxForm rule_syntax = rules_syntax;
            Object syntax_rule = rules_pair.getCar();
            while (syntax_rule instanceof SyntaxForm) {
                rule_syntax = (SyntaxForm) syntax_rule;
                syntax_rule = rule_syntax.getDatum();
            }
            if (! (syntax_rule instanceof Pair)) {
                tr.error('e', "missing pattern in syntax rule #" + i);
                return;
            }
            // SyntaxForm, if any, wrapping the current rule's pattern.
            SyntaxForm pattern_syntax = rule_syntax;
            Pair syntax_rule_pair = (Pair) syntax_rule;
            Object pattern = syntax_rule_pair.getCar();

            String save_filename = tr.getFileName();
            int save_line = tr.getLineNumber();
            int save_column = tr.getColumnNumber();

            try {
                // SyntaxForm, if any, wrapping the current rule's template.
                SyntaxForm template_syntax = rule_syntax;
                tr.setLine(syntax_rule_pair);
                syntax_rule = syntax_rule_pair.getCdr();
                while (syntax_rule instanceof SyntaxForm) {
                    template_syntax = (SyntaxForm) syntax_rule;
                    syntax_rule = template_syntax.getDatum();
                }
                if (! (syntax_rule instanceof Pair)) {
                    tr.error('e', "missing template in syntax rule #" + i);
                    return;
                }
                syntax_rule_pair = (Pair) syntax_rule;
                if (syntax_rule_pair.getCdr() != LList.Empty) {
                    Object save = tr.pushPositionOf(syntax_rule_pair.getCdr());
                    tr.error('e', "junk after syntax rule #" + i);
                    tr.popPositionOf(save);
                    return;
                }
                Object template = syntax_rule_pair.getCar();

                PatternScope patternScope = PatternScope.push(tr);
                tr.push(patternScope);
                try {
                    while (pattern instanceof SyntaxForm) {
                        pattern_syntax = (SyntaxForm) pattern;
                        pattern = pattern_syntax.getDatum();
                    }

                    StringBuilder programbuf = new StringBuilder();

                    // In R5RS syntax-rules, the initial name is neither a
                    // pattern variable or a literal identifier, so ignore it.
                    if (pattern instanceof Pair) {
                        Pair p = (Pair) pattern;
                        programbuf.append((char) ((1 << 3)
                                                  | SyntaxPattern.MATCH_PAIR));
                        programbuf.append((char) SyntaxPattern.MATCH_IGNORE);
                        pattern = p.getCdr();
                    } else {
                        // Identifier macro? FIXME
                        tr.error('e', "pattern does not start with name");
                        return;
                    }
                    SyntaxPattern spattern =
                        new SyntaxPattern(programbuf, pattern, pattern_syntax,
                                          ellipsis, literal_identifiers, tr);

                    this.rules[i] =
                        new SyntaxRule(spattern, template,
                                       template_syntax, ellipsis, tr);
                } finally {
                    PatternScope.pop(tr);
                    tr.pop();
                }
            } finally {
                tr.setLine(save_filename, save_line, save_column);
            }
        }

        // Calculate maxVars:
        for (int i = this.rules.length;  --i >= 0; ) {
            int size = this.rules[i].patternNesting.length();
            if (size > maxVars)
                maxVars = size;
        }
    }

    /* Recursively translate a pattern in a syntax-rule to a Pattern object.
     * @param pattern the the pattern to translate
     * @param literal_identifiers the literals of the syntax-rule
     * @param nesting the depth of ... we are inside
     * @param tr  the current Translator
     * @return the translated Pattern
     */

    public Object apply1(Object arg) {
        if (arg instanceof SyntaxForm) {
            SyntaxForm sf = (SyntaxForm) arg;
            Translator tr = (Translator) Compilation.getCurrent();
            ScopeExp save_scope = tr.currentScope();
            tr.setCurrentScope(sf.getScope());
            try {
                return expand(sf, tr);
            } finally {
                tr.setCurrentScope(save_scope);
            }
        } else
            return expand(arg, (Translator) Compilation.getCurrent());
    }

    /* DEBUGGING:
    private void printElement(Object el, StringBuffer sb) {
        if (el instanceof Object[]) {
            Object[] arr = (Object[]) el;
            sb.append('{');
            for (int i = 0;  i < arr.length;  i++) {
                if (i != 0)
                    sb.append(", ");
                printElement(arr[i], sb);
            }
            sb.append('}');
        } else
            sb.append(el);
    }
    END DEBUGGING */

    public Object expand(Object obj, Translator tr) {
        Object[] vars = new Object[maxVars];
        Macro macro = (Macro) tr.getCurrentSyntax();
        /* DEBUGGING:
           System.err.println("match "+macro+" args:"+obj+" maxVars:"+maxVars);
           System.err.flush();
        */
        for (int i = 0;  i < rules.length;  i++) {
            SyntaxRule rule = rules[i];
            if (rule==null)
                return new ErrorExp("error defining "+macro);
            // check that literals have correct binding - FIXME!!
            Pattern pattern = rule.pattern;
            boolean matched = pattern.match (obj, vars, 0);
            if (matched) {
                if (true) {  // DEBUGGING
                    /*
                    OutPort err = OutPort.errDefault();
                    StringBuffer sb = new StringBuffer();
                    sb.append("{Expand "+macro + " rule#" + i
                              +" - matched variables: ");
                    for (int j = 0;  j < rule.pattern.varCount;  j++) {
                        if (j > 0)  sb.append("; ");
                        sb.append(j);  sb.append(": ");
                        printElement(vars[j], sb);
                    }
                    sb.append('}');
                    err.println(sb);
                    err.flush();
                    */
                }

                if (true) {
                    /* DEBUGGING:
                    OutPort err = OutPort.errDefault();
                    err.print("Expanding ");  err.println(getName());
                    rule.print_template_program(null, err);
                    err.flush();
                    */
                }
                Object expansion = rule.execute(vars, tr);

                if (false) { // DEBUGGING:
                    OutPort err = OutPort.errDefault();
                    err.print("{Expansion of ");
                    err.print(macro);
                    err.println(":");
                    err.startLogicalBlock("  ", "}", 2);
                    DisplayFormat.schemeWriteFormat.writeObject(expansion, err);
                    err.endLogicalBlock("}");
                    err.println();
                    err.flush();
                }
                return expansion;
            }
        }
        /* DEBUGGING:
        System.err.println("no matching syntax-rule for "
                           + getName());
        System.err.flush();
        */
        return tr.syntaxError ("no matching syntax-rule for "
                               + getName());
    }

    public void print(Consumer out) {
        out.write("#<macro ");
        ReportFormat.print(getName(), out);
        out.write('>');
    }

    /**
     * @serialData Write literal_identifiers followed by rules,
     *   using writeObject.
     */
    public void writeExternal(ObjectOutput out) throws IOException {
        out.writeObject(literal_identifiers);
        out.writeObject(rules);
        out.writeInt(maxVars);
        out.writeObject(getSymbol());
    }

    public void readExternal(ObjectInput in)
        throws IOException, ClassNotFoundException {
        literal_identifiers = (Object[]) in.readObject();
        rules = (SyntaxRule[]) in.readObject();
        maxVars = in.readInt();
        Object name = in.readObject();
        if (name != null)
            setSymbol(name);
    }
}