parser

Type Members

1. class TwirlParser extends AnyRef

   

   TwirlParser is a recursive descent parser for a modified grammar of the Play2 template language as loosely defined here and more rigorously defined by the original template parser, play.templates.ScalaTemplateCompiler.TemplateParser.

   TwirlParser is a recursive descent parser for a modified grammar of the Play2 template language as loosely defined here and more rigorously defined by the original template parser, play.templates.ScalaTemplateCompiler.TemplateParser. TwirlParser is meant to be a near drop in replacement for play.templates.ScalaTemplateCompiler.TemplateParser.

   The original grammar, as reversed-engineered from play.templates.ScalaTemplateCompiler.TemplateParser, is defined as follows:

   parser : comment? whitespace? ('@' parentheses+)? templateContent
   templateContent : (importExpression | localDef | template | mixed)*
   templateDeclaration : '@' identifier squareBrackets? parentheses*
   localDef : templateDeclaration (' ' | '\t')* '=' (' ' | '\t') scalaBlock
   template : templateDeclaration (' ' | '\t')* '=' (' ' | '\t') '{' templateContent '}'
   mixed : (comment | scalaBlockDisplayed | caseExpression | matchExpression | forExpression | safeExpression | plain | expression) | ('{' mixed* '}')
   scalaBlockDisplayed : scalaBlock
   scalaBlockChained : scalaBlock
   scalaBlock : '@' brackets
   importExpression : '@' 'import ' .* '\r'? '\n'
   caseExpression : whitespace? 'case' .+ '=>' block whitespace?
   forExpression : '@' "for" parentheses block
   matchExpression : '@' (simpleExpr | complexExpr) whitespaceNoBreak 'match' block
   simpleExpr : methodCall expressionPart*
   complexExpr : parentheses
   safeExpression : '@' parentheses
   elseCall : whitespaceNoBreak "else" whitespaceNoBreak?
   chainedMethods : ('.' methodCall)+
   expressionPart : chainedMethods | block | (whitespaceNoBreak scalaBlockChained) | elseCall | parentheses
   expression : '@' methodCall expressionPart*
   methodCall : identifier squareBrackets? parentheses?
   blockArgs : [^'=>' '\n']* '=>'
   block : whitespaceNoBreak '{' blockArgs? mixed* '}'
   brackets : '{' (brackets | [^'}'])* '}'
   comment : '@*' [^'*@']* '*@'
   parentheses : '(' (parentheses | [^')'])* ')'
   squareBrackets : '[' (squareBrackets | [^']'])* ']'
   plain : ('@@' | ([^'@'] [^'{' '}']))+
   whitespaceNoBreak : [' ' '\t']+
   identifier : javaIdentStart javaIdentPart* // see java docs for what these two rules mean

   TwirlParser implements a slightly modified version of the above grammar that removes some back-tracking within the 'mixed' non-terminal. It is defined as follows:

   parser : comment? whitespace? ('@' parentheses+)? templateContent
   templateContent : (importExpression | localDef | template | mixed)*
   templateDeclaration : '@' identifier squareBrackets? parentheses*
   localDef : templateDeclaration (' ' | '\t')* '=' (' ' | '\t') scalaBlock
   template : templateDeclaration (' ' | '\t')* '=' (' ' | '\t') '{' templateContent '}'
   mixed : (comment | scalaBlockDisplayed | forExpression | matchExpOrSafeExpOrExpr | caseExpression | plain) | ('{' mixed* '}')
   matchExpOrSafeExpOrExpr : (expression | safeExpression) (whitespaceNoBreak 'match' block)?
   scalaBlockDisplayed : scalaBlock
   scalaBlockChained : scalaBlock
   scalaBlock : '@' brackets
   importExpression : '@' 'import ' .* '\r'? '\n'
   caseExpression : (whitespace? 'case' .+ '=>' block whitespace?) | whitespace
   forExpression : '@' "for" parentheses block
   simpleExpr : methodCall expressionPart*
   complexExpr : parentheses
   safeExpression : '@' parentheses
   elseCall : whitespaceNoBreak? "else" whitespaceNoBreak?
   elseIfCall : whitespaceNoBreak? "else if" parentheses  whitespaceNoBreak?
   chainedMethods : ('.' methodCall)+
   expressionPart : chainedMethods | block | (whitespaceNoBreak scalaBlockChained) | elseIfCall | elseCall | parentheses
   expression : '@' methodCall expressionPart*
   methodCall : identifier squareBrackets? parentheses?
   blockArgs : [^'=>' '\n']* '=>'
   block : whitespaceNoBreak? '{' blockArgs? mixed* '}'
   brackets : '{' (brackets | [^'}'])* '}'
   comment : '@*' [^'*@']* '*@'
   parentheses : '(' (parentheses | [^')'])* ')'
   squareBrackets : '[' (squareBrackets | [^']'])* ']'
   plain : ('@@' | '@}' | ([^'@'] [^'{' '}']))+
   whitespaceNoBreak : [' ' '\t']+
   identifier : javaIdentStart javaIdentPart* // see java docs for what these two rules mean

   TwirlParser can detect several type of parse errors and provides line information. In all cases, the parser will continue parsing the best it can after encountering an error. The following errors are what can be detected:

   • EOF found when more input was expected.
   • Unmatched curly braces
   • Missing blocks after case and match statements
   • Invalid ("alone") '@' symbols.