christoph/lecture-compilers
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parse semantic actions

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ChUrl
2020-12-11 13:34:31 +01:00
parent 66e672d142
commit e8d88dda40
1 changed files with 47 additions and 7 deletions
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54
src/main/java/parser/grammar/Grammar.java
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@ -1,16 +1,19 @@
package parser.grammar;
import util.tools.Logger;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;
import static util.tools.Logger.log;
public class Grammar {
private final Set<String> terminals;
@ -18,6 +21,8 @@ public class Grammar {
private final String startSymbol;
private final String epsilonSymbol;
private final Map<String, Set<String>> actions;
private final Set<GrammarRule> rules;
public Grammar(Set<String> terminals, Set<String> nonterminals,
@ -27,6 +32,18 @@ public class Grammar {
this.nonterminals = nonterminals;
this.startSymbol = startSymbol;
this.epsilonSymbol = epsilonSymbol;
this.actions = null;
this.rules = rules;
}
public Grammar(Set<String> terminals, Set<String> nonterminals,
String startSymbol, String epsilonSymbol,
Map<String, Set<String>> actions, Set<GrammarRule> rules) {
this.terminals = terminals;
this.nonterminals = nonterminals;
this.startSymbol = startSymbol;
this.epsilonSymbol = epsilonSymbol;
this.actions = actions;
this.rules = rules;
}
@ -44,12 +61,13 @@ public class Grammar {
Set<String> terminals = new HashSet<>();
Set<String> nonterminals = new HashSet<>();
Map<String, Set<String>> actions = new HashMap<>();
Set<GrammarRule> rules = new HashSet<>();
Logger.log("Parsing Grammar from File:");
log("Parsing Grammar from File:");
for (String line : lines) {
Logger.log("Parsed: " + line);
log("Parsed: " + line);
if (line.startsWith("START:")) {
@ -64,14 +82,32 @@ public class Grammar {
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"
// "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();
int open = leftside.indexOf('[');
int close = leftside.indexOf(']');
// Aus "S[C R]" wird flags = {"C", "R"} extrahiert
String[] flags = leftside.substring(open + 1, close).split(" ");
List<String> flagList = Arrays.stream(flags)
.map(String::trim)
.filter(flag -> !flag.isEmpty())
.collect(Collectors.toList());
// "S[C R]" wird zu "S"
leftside = leftside.substring(0, open);
actions.put(leftside, new HashSet<>());
actions.get(leftside).addAll(flagList);
if (!flagList.isEmpty()) {
log("Registered actions for " + leftside + ": " + flagList + "\n");
}
// "E T2 | epsilon" wird zu prods[0] = "E T2" und prods[1] = "epsilon"
String[] prods = rightside.split("\\|");
@ -81,7 +117,7 @@ public class Grammar {
}
}
}
Logger.log("-".repeat(100));
log("-".repeat(100));
return new Grammar(terminals, nonterminals,
startSymbol, epsilonSymbol,
@ -127,4 +163,8 @@ public class Grammar {
.map(GrammarRule::getLeftside)
.collect(Collectors.toUnmodifiableSet());
}
public Set<String> getActions(String leftside) {
return this.actions == null ? Collections.emptySet() : this.actions.get(leftside);
}
}