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Further improvements to auto-label generic usage, return Collections.emptyList() instead of null when no children are found

This commit is contained in:
Sam Harwell 2012-02-15 12:31:43 -06:00
parent 0bbb7101ba
commit 685cf7b7d5
2 changed files with 46 additions and 17 deletions
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59
runtime/Java/src/org/antlr/v4/runtime/ParserRuleContext.java
View File

@ -176,15 +176,18 @@ public class ParserRuleContext<Symbol> extends RuleContext {
@Override
public ParseTree getChild(int i) {
return children!=null ? children.get(i) : null;
return children!=null && i>=0 && i<children.size() ? children.get(i) : null;
}
public <T extends ParseTree> T getChild(Class<? extends T> ctxType, int i) {
if ( children==null || i < 0 || i >= children.size() ) {
return null;
}
public <T> T getChild(Class<? extends T> ctxType, int i) {
if ( children==null ) throw new UnsupportedOperationException("there are no children");
int j = -1; // what element have we found with ctxType?
for (Object o : children) {
for (ParseTree o : children) {
if ( ctxType.isInstance(o) ) {
j = j+1;
j++;
if ( j == i ) {
return ctxType.cast(o);
}
@ -194,9 +197,12 @@ public class ParserRuleContext<Symbol> extends RuleContext {
}
public Token getToken(int ttype, int i) {
if ( children==null ) throw new UnsupportedOperationException("there are no children");
if ( children==null || i < 0 || i >= children.size() ) {
return null;
}
int j = -1; // what token with ttype have we found?
for (Object o : children) {
for (ParseTree o : children) {
if ( o instanceof TerminalNode<?> ) {
TerminalNode<?> tnode = (TerminalNode<?>)o;
if ( tnode.getSymbol() instanceof Token ) {
@ -210,18 +216,33 @@ public class ParserRuleContext<Symbol> extends RuleContext {
}
}
}
return null;
}
public List<Token> getTokens(int ttype) {
if ( children==null ) throw new UnsupportedOperationException("there are no children");
public List<? extends Token> getTokens(int ttype) {
if ( children==null ) {
return Collections.emptyList();
}
List<Token> tokens = null;
for (Object o : children) {
if ( o instanceof Token ) {
if ( tokens==null ) tokens = new ArrayList<Token>();
tokens.add((Token)o);
for (ParseTree o : children) {
if ( o instanceof TerminalNode<?> ) {
TerminalNode<?> tnode = (TerminalNode<?>)o;
if ( tnode.getSymbol() instanceof Token ) {
Token symbol = (Token)tnode.getSymbol();
if ( tokens==null ) {
tokens = new ArrayList<Token>();
}
tokens.add(symbol);
}
}
}
if ( tokens==null ) {
return Collections.emptyList();
}
return tokens;
}
@ -230,9 +251,12 @@ public class ParserRuleContext<Symbol> extends RuleContext {
}
public <T extends ParserRuleContext<?>> List<? extends T> getRuleContexts(Class<? extends T> ctxType) {
if ( children==null ) throw new UnsupportedOperationException("there are no children");
if ( children==null ) {
return Collections.emptyList();
}
List<T> contexts = null;
for (Object o : children) {
for (ParseTree o : children) {
if ( ctxType.isInstance(o) ) {
if ( contexts==null ) {
contexts = new ArrayList<T>();
@ -241,6 +265,11 @@ public class ParserRuleContext<Symbol> extends RuleContext {
contexts.add(ctxType.cast(o));
}
}
if ( contexts==null ) {
return Collections.emptyList();
}
return contexts;
}

4
tool/resources/org/antlr/v4/tool/templates/codegen/Java/Java.stg
View File

@ -496,7 +496,7 @@ RuleContextListDecl(rdecl) ::= "public List\<<rdecl.ctxName>> <rdecl.name> = new
ContextTokenGetterDecl(t) ::=
"public Token <t.name>() { return getToken(<parser.name>.<t.name>, 0); }"
ContextTokenListGetterDecl(t) ::=
"public List\<Token> <t.name>() { return getTokens(<parser.name>.<t.name>); }"
"public List\<? extends Token> <t.name>() { return getTokens(<parser.name>.<t.name>); }"
ContextTokenListIndexedGetterDecl(t) ::= <<
public Token <t.name>(int i) {
return getToken(<parser.name>.<t.name>, i);
@ -508,7 +508,7 @@ public <r.ctxName> <r.name>() {
}
>>
ContextRuleListGetterDecl(r) ::= <<
public List\<<r.ctxName>\> <r.name>() {
public List\<? extends <r.ctxName>\> <r.name>() {
return (List\<<r.ctxName>\>)getRuleContexts(<r.ctxName>.class);
}
>>