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improve grammar parsing

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ChUrl
2020-12-07 20:57:26 +01:00
parent cec76298e8
commit 509031ab31
1 changed files with 31 additions and 22 deletions
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53
src/main/java/parser/grammar/Grammar.java
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@ -35,33 +35,42 @@ public class Grammar {
.collect(Collectors.toUnmodifiableList());
try {
String startSymbol = lines.get(0).split(" ")[1];
String epsilonSymbol = lines.get(1).split(" ")[1];
String[] term = lines.get(2).split(" ");
term = Arrays.copyOfRange(term, 1, term.length);
Set<String> terminals = new HashSet<>(Arrays.asList(term));
String[] nterm = lines.get(3).split(" ");
nterm = Arrays.copyOfRange(nterm, 1, nterm.length);
Set<String> nonterminals = new HashSet<>(Arrays.asList(nterm));
String startSymbol = "";
String epsilonSymbol = "";
Set<String> terminals = new HashSet<>();
Set<String> nonterminals = new HashSet<>();
Set<GrammarRule> rules = new HashSet<>();
for (int i = 4; i < lines.size(); i++) {
// "S -> E T2 | EPS" wird zu leftside = "S" und rightside = "E T2 | epsilon"
String[] split = lines.get(i)
.replaceAll("EPS", epsilonSymbol)
.split("->");
for (String line : lines) {
String leftside = split[0].trim();
String rightside = split[1].trim();
if (line.startsWith("START:")) {
// "E T2 | epsilon" wird zu prods[0] = "E T2" und prods[1] = "epsilon"
String[] prods = rightside.split("\\|");
startSymbol = line.split(" ")[1];
} else if (line.startsWith("EPS:")) {
for (String prod : prods) {
GrammarRule rule = new GrammarRule(leftside, prod.split(" "));
rules.add(rule);
epsilonSymbol = line.split(" ")[1];
} else if (line.startsWith("TERM:")) {
terminals.addAll(Arrays.stream(line.split(" ")).skip(1).collect(Collectors.toSet()));
} else if (line.startsWith("NTERM:")) {
nonterminals.addAll(Arrays.stream(line.split(" ")).skip(1).collect(Collectors.toSet()));
} else {
// "S -> E T2 | EPS" wird zu leftside = "S" und rightside = "E T2 | epsilon"
String[] split = line.replaceAll("EPS", epsilonSymbol)
.split("->");
String leftside = split[0].trim();
String rightside = split[1].trim();
// "E T2 | epsilon" wird zu prods[0] = "E T2" und prods[1] = "epsilon"
String[] prods = rightside.split("\\|");
for (String prod : prods) {
GrammarRule rule = new GrammarRule(leftside, prod.split(" "));
rules.add(rule);
}
}
}