Files
lecture-compilers/src/main/java/parser/LL1ParsingTable.java
2020-12-07 23:34:22 +01:00

122 lines
3.8 KiB
Java

package parser;
import parser.grammar.Grammar;
import parser.grammar.LL1GrammarAnalyzer;
import java.util.AbstractMap.SimpleEntry;
import java.util.Formatter;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.stream.Collectors;
public class LL1ParsingTable implements ILL1ParsingTable {
private final Grammar grammar;
private final Map<Entry<String, String>, String> parsetable;
public LL1ParsingTable(Grammar grammar, Map<Entry<String, String>, String> parsetable) {
this.grammar = grammar;
this.parsetable = parsetable;
}
public static ILL1ParsingTable fromGrammar(Grammar grammar) {
LL1GrammarAnalyzer analyzer = new LL1GrammarAnalyzer(grammar);
return analyzer.getTable();
}
@Override
public String get(String nonterminal, String terminal) {
return this.parsetable.get(new SimpleEntry<>(nonterminal, terminal));
}
@Override
public String getStartSymbol() {
return this.grammar.getStartSymbol();
}
@Override
public Set<String> getNonterminals() {
return this.grammar.getNonterminals();
}
@Override
public Set<String> getTerminals() {
return this.grammar.getTerminals();
}
@Override
public String getEpsilon() {
return this.grammar.getEpsilonSymbol();
}
@Override
public String toString() {
StringBuilder output = new StringBuilder();
Formatter format = new Formatter(output);
List<String> inputSymbols = this.parsetable.keySet().stream()
.map(Entry::getValue)
.distinct()
.collect(Collectors.toList());
// Determine margins
Map<String, Integer> margins = new HashMap<>();
margins.put("NTERM", 0);
for (String terminal : inputSymbols) {
margins.put(terminal, 0);
}
for (String nonterminal : this.grammar.getNonterminals()) {
margins.put("NTERM", Math.max(margins.get("NTERM"), nonterminal.length()));
for (String terminal : inputSymbols) {
String prod = this.parsetable.get(new SimpleEntry<>(nonterminal, terminal));
int length;
if (prod == null) {
length = 0;
} else {
length = prod.length();
}
margins.put(terminal, Math.max(margins.get(terminal), length));
margins.put(terminal, Math.max(margins.get(terminal), terminal.length()));
}
}
output.append(" ".repeat(margins.get("NTERM")))
.append("| ");
for (String terminal : inputSymbols) {
format.format("%-Xs ".replaceAll("X", String.valueOf(margins.get(terminal))), terminal);
}
output.append("|\n");
output.append("-".repeat(margins.get("NTERM")))
.append("+");
for (String terminal : inputSymbols) {
output.append("-".repeat(margins.get(terminal)));
}
output.append("-".repeat(inputSymbols.size() + 1))
.append("+")
.append("\n");
for (String nonterminal : this.grammar.getNonterminals()) {
format.format("%-Xs| ".replaceAll("X", String.valueOf(margins.get("NTERM"))), nonterminal);
for (String terminal : inputSymbols) {
String prod = this.parsetable.get(new SimpleEntry<>(nonterminal, terminal));
format.format("%-Xs ".replaceAll("X", String.valueOf(margins.get(terminal))), prod == null ? " ".repeat(9) : prod);
}
output.append("|\n");
}
format.close();
return output.toString();
}
}