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Modify Painless grammar to support right brackets as statement delimiters #29566

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Merged
merged 3 commits into from
Apr 18, 2018
Merged

Modify Painless grammar to support right brackets as statement delimiters #29566

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328b671
Modify Painless grammar to support right brackets as statement
jdconrad Apr 17, 2018
814334c
Merge branch 'master' into semicolon
jdconrad Apr 17, 2018
22e8da3
Merge branch 'master' into semicolon
jdconrad Apr 18, 2018
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47 changes: 24 additions & 23 deletions modules/lang-painless/src/main/antlr/PainlessParser.g4
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,7 @@ parser grammar PainlessParser;
options { tokenVocab=PainlessLexer; }

source
: function* statement* EOF
: function* statement* dstatement? EOF
;

function
Expand All @@ -33,23 +33,31 @@ parameters
: LP ( decltype ID ( COMMA decltype ID )* )? RP
;

statement
: rstatement
| dstatement SEMICOLON
;

// Note we use a predicate on the if/else case here to prevent the
// "dangling-else" ambiguity by forcing the 'else' token to be consumed
// as soon as one is found. See (https://en.wikipedia.org/wiki/Dangling_else).
statement
rstatement
: IF LP expression RP trailer ( ELSE trailer | { _input.LA(1) != ELSE }? ) # if
| WHILE LP expression RP ( trailer | empty ) # while
| DO block WHILE LP expression RP delimiter # do
| FOR LP initializer? SEMICOLON expression? SEMICOLON afterthought? RP ( trailer | empty ) # for
| FOR LP decltype ID COLON expression RP trailer # each
| FOR LP ID IN expression RP trailer # ineach
| declaration delimiter # decl
| CONTINUE delimiter # continue
| BREAK delimiter # break
| RETURN expression delimiter # return
| TRY block trap+ # try
| THROW expression delimiter # throw
| expression delimiter # expr
;

dstatement
: DO block WHILE LP expression RP # do
| declaration # decl
| CONTINUE # continue
| BREAK # break
| RETURN expression # return
| THROW expression # throw
| expression # expr
;

trailer
Expand All @@ -58,7 +66,7 @@ trailer
;

block
: LBRACK statement* RBRACK
: LBRACK statement* dstatement? RBRACK
;

empty
Expand Down Expand Up @@ -90,11 +98,6 @@ trap
: CATCH LP TYPE ID RP block
;

delimiter
: SEMICOLON
| EOF
;

expression
: unary # single
| expression ( MUL | DIV | REM ) expression # binary
Expand Down Expand Up @@ -169,8 +172,8 @@ braceaccess
;

arrayinitializer
: NEW TYPE ( LBRACE expression RBRACE )+ ( postdot postfix* )? # newstandardarray
| NEW TYPE LBRACE RBRACE LBRACK ( expression ( COMMA expression )* )? SEMICOLON? RBRACK postfix* # newinitializedarray
: NEW TYPE ( LBRACE expression RBRACE )+ ( postdot postfix* )? # newstandardarray
| NEW TYPE LBRACE RBRACE LBRACK ( expression ( COMMA expression )* )? RBRACK postfix* # newinitializedarray
;

listinitializer
Expand Down Expand Up @@ -206,10 +209,8 @@ lamtype
;

funcref
: TYPE REF ID # classfuncref // reference to a static or instance method,
// e.g. ArrayList::size or Integer::compare
| decltype REF NEW # constructorfuncref // reference to a constructor, e.g. ArrayList::new
| ID REF ID # capturingfuncref // reference to an instance method, e.g. object::toString
// currently limited to capture of a simple variable (id).
| THIS REF ID # localfuncref // reference to a local function, e.g. this::myfunc
: TYPE REF ID # classfuncref
| decltype REF NEW # constructorfuncref
| ID REF ID # capturingfuncref
| THIS REF ID # localfuncref
;
40 changes: 4 additions & 36 deletions ...s/lang-painless/src/main/java/org/elasticsearch/painless/antlr/EnhancedPainlessLexer.java
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Expand Up @@ -44,36 +44,18 @@ final class EnhancedPainlessLexer extends PainlessLexer {
private final String sourceName;
private final Definition definition;

private Token stashedNext = null;
private Token previous = null;
private Token current = null;

EnhancedPainlessLexer(CharStream charStream, String sourceName, Definition definition) {
super(charStream);
this.sourceName = sourceName;
this.definition = definition;
}

public Token getPreviousToken() {
return previous;
}

@Override
public Token nextToken() {
if (stashedNext != null) {
previous = stashedNext;
stashedNext = null;
return previous;
}
Token next = super.nextToken();
if (insertSemicolon(previous, next)) {
stashedNext = next;
previous = _factory.create(new Pair<TokenSource, CharStream>(this, _input), PainlessLexer.SEMICOLON, ";",
Lexer.DEFAULT_TOKEN_CHANNEL, next.getStartIndex(), next.getStopIndex(), next.getLine(), next.getCharPositionInLine());
return previous;
} else {
previous = next;
return next;
}
current = super.nextToken();
return current;
}

@Override
Expand Down Expand Up @@ -101,7 +83,7 @@ protected boolean isSimpleType(String name) {

@Override
protected boolean slashIsRegex() {
Token lastToken = getPreviousToken();
Token lastToken = current;
if (lastToken == null) {
return true;
}
Expand All @@ -120,18 +102,4 @@ protected boolean slashIsRegex() {
return true;
}
}

private static boolean insertSemicolon(Token previous, Token next) {
if (previous == null || next.getType() != PainlessLexer.RBRACK) {
return false;
}
switch (previous.getType()) {
case PainlessLexer.RBRACK: // };} would be weird!
case PainlessLexer.SEMICOLON: // already have a semicolon, no need to add one
case PainlessLexer.LBRACK: // empty blocks don't need a semicolon
return false;
default:
return true;
}
}
}
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