expressions.grm

/**
## Expressions

<!--See [Expressions](expressions.html)-->

### Precedence

| Precedence | Title | Symbols |
|------------|-------|---------|
| Highest    | Postfix | `++`, `--`, `.`, `?.`, `?` |
| | Prefix | `-`, `+`, `++`, `--`, `!`, [`@label`](#LabelName), `@`, `@@` |
| | Type RHS | `:`, `as`, `as?` |
| | Multiplicative | `*`, `/`, `%` |
| | Additive | `+`, `-` |
| | Range | `..` |
| | Infix function | [`SimpleName`](#SimpleName) |
| | Elvis | `?:` |
| | Named checks | `in`, `!in`, `is`, `!is` |
| | Comparison | `<`, `>`, `<=`, `>=` |
| | Equality | `==`, `\!==` |
| | Conjunction | `&&` |
| | Disjunction | `||` |
| Lowest | Assignment | `=`, `+=`, `-=`, `*=`, `/=`, `%=` |

### Rules

*/

/*
Decreasing precedence:
  memberAccessOperation
  postfixUnaryOperation
  prefixUnaryOperation
  multiplicativeOperation
  additiveOperation
  ".."
  SimpleName
  "?:"
  namedInfixOrTypeOperation
  comparisonOperation
  equalityOperation
  "&&"
  "||"
  assignmentOperator
*/

expression
  : disjunction (assignmentOperator disjunction)*
  ;

disjunction
  : conjunction ("||" conjunction)*
  ;

conjunction
  : equalityComparison ("&&" equalityComparison)*
  ;

equalityComparison
  : comparison (equalityOperation comparison)*
  ;

comparison
  : namedInfix (comparisonOperation namedInfix)*
  ;

namedInfix
  : elvisExpression (inOperation elvisExpression)*
  : elvisExpression (isOperation isRHS)?
  ;

elvisExpression
  : infixFunctionCall ("?:" infixFunctionCall)*
  ;

infixFunctionCall
  : rangeExpression (SimpleName rangeExpression)*
  ;

rangeExpression
  : additiveExpression (".." additiveExpression)*
  ;

additiveExpression
  : multiplicativeExpression (additiveOperation multiplicativeExpression)*
  ;

multiplicativeExpression
  : typeRHS (multiplicativeOperation typeRHS)*
  ;

typeRHS
  : prefixUnaryExpression (typeOperation prefixUnaryExpression)*
  ;

prefixUnaryExpression
  : prefixUnaryOperation* postfixUnaryExpression
  ;

postfixUnaryExpression
  : atomicExpression postfixUnaryOperation*
  : callableReference postfixUnaryOperation*
  ;

// TODO: callSuffix is forbidden after callableReference, since parentheses will be used to provide parameter types
callableReference
  : (userType "?"*)? "::" SimpleName
  ;

// !!! When you add here, remember to update the FIRST set in the parser
atomicExpression
  : "(" expression ")"
  : literalConstant
  : functionLiteral
  : "this" label?
  : "super" ("<" type ">")? label?
  : if
  : when
  : try
  : objectLiteral
  : jump
  : loop
  : SimpleName
  : FieldName
  : "package" // for the root package
  ;

label
  : "@"
  : "@@"
  : LabelName
  ;

literalConstant
  : "true" | "false"
  : stringTemplate
  : NoEscapeString
  : IntegerLiteral
  : HexadecimalLiteral
  : CharacterLiteral
  : FloatLiteral
  : "null"
  ;

stringTemplate
  : "\"" stringTemplateElement* "\""
  ;

stringTemplateElement
  : RegularStringPart
  : ShortTemplateEntrySTART (SimpleName | "this")
  : EscapeSequence
  : longTemplate
  ;

longTemplate
  : "${" expression "}"
  ;

isRHS
  : type
  ;

declaration
  : function
  : property
  : class
  : typeAlias
  : object
  ;

statement
  : declaration
  : expression
  ;

multiplicativeOperation
  : "*" : "/" : "%"
  ;

additiveOperation
  : "+" : "-"
  ;

inOperation
  : "in" : "!in"
  ;

typeOperation
  : "as" : "as?" : ":"
  ;

isOperation
  : "is" : "!is"
  ;

comparisonOperation
  : "<" : ">" : ">=" : "<="
  ;

equalityOperation
  : "!=" : "=="
  ;

assignmentOperator
  : "="
  : "+=" : "-=" : "*=" : "/=" : "%="
  ;

prefixUnaryOperation
  : "-" : "+"
  : "++" : "--"
  : "!"  // No ~
  : annotations // mandatory
  : label
  ;

postfixUnaryOperation
  : "++" : "--" : "!!"
  : callSuffix
  : arrayAccess
  : memberAccessOperation postfixUnaryExpression // TODO: Review
  ;

callSuffix
  : typeArguments? valueArguments (label? functionLiteral)
  : typeArguments (label? functionLiteral)
  ;

memberAccessOperation
  : "." : "?." : "?"
  ;

typeArguments
  : "<" type{","} ">"
  ;

valueArguments
  : "(" (SimpleName "=")? "*"? expression{","} ")"
  ;

jump
  : "throw" expression
  : "return" label? expression?
  : "continue" label?
  : "break" label?
// yield ?
  ;

// one can use "it" as a parameter name
functionLiteral
  : "{" statements "}"
  : "{" (modifiers SimpleName){","} "->" statements "}"
  : "{" (type ".")? "(" (modifiers SimpleName (":" type)?){","} ")" (":" type)? "->" statements "}"
  ;

statements
  : SEMI* statement{SEMI+} SEMI*
  ;

constructorInvocation
  : userType callSuffix
  ;

arrayAccess
  : "[" expression{","} "]"
  ;

objectLiteral
  : "object" (":" delegationSpecifier{","})? classBody // Cannot make class body optional: foo(object : F, A)
  ;

/* Factory methods:

objectLiteral
  : "object" delegationSpecifier{","} ("{" objectLiteralMember{","} "}")?
  ;

objectLiteralMember
  : memberDeclaration
  : factoryMethod
  ;

factoryMethod
  : accessModifier? SimpleName typeParameters? functionParameters functionBody
  ;