|
|
@@ -0,0 +1,152 @@
|
|
|
+.. _doc_gdscript_grammar:
|
|
|
+
|
|
|
+GDScript grammar
|
|
|
+================
|
|
|
+
|
|
|
+This is the formal grammar of GDScript written in `EBNF <https://en.wikipedia.org/wiki/Extended_Backus%E2%80%93Naur_form>`_,
|
|
|
+for reference purposes.
|
|
|
+
|
|
|
+.. note:: This grammar is descriptive only, derived from the reference
|
|
|
+ documentation and current implementation. The GDScript parser is
|
|
|
+ **not** generated from a grammar definition. Inconsistencies here
|
|
|
+ likely mean an error in this grammar, not a bug in GDScript.
|
|
|
+
|
|
|
+.. code-block:: ebnf
|
|
|
+
|
|
|
+ (* GDScript EBNF grammar.
|
|
|
+ Uppercase words are terminals generated by the tokenizer.
|
|
|
+ INDENT/DEDENT are not generated by the tokenizer yet, but they are added
|
|
|
+ here for reading convenience.
|
|
|
+ Naturally, this only cover syntax. Semantics can't be inferred from this
|
|
|
+ description.
|
|
|
+ *)
|
|
|
+
|
|
|
+ program = [ inheritance NEWLINE ] [ className ] { topLevelDecl } ;
|
|
|
+
|
|
|
+ inheritance = "extends" ( IDENTIFIER | STRING ) { "." IDENTIFIER } ;
|
|
|
+ className = "class_name" IDENTIFIER [ "," STRING ] NEWLINE ;
|
|
|
+
|
|
|
+ topLevelDecl
|
|
|
+ = classVarDecl
|
|
|
+ | constDecl
|
|
|
+ | signalDecl
|
|
|
+ | enumDecl
|
|
|
+ | methodDecl
|
|
|
+ | constructorDecl
|
|
|
+ | innerClass
|
|
|
+ | "tool"
|
|
|
+ ;
|
|
|
+
|
|
|
+ classVarDecl = [ "onready" ] [ export ] "var" IDENTIFIER [ ":" typeHint ]
|
|
|
+ [ "=" expression ] [ setget ] NEWLINE ;
|
|
|
+ setget = "setget" [ IDENTIFIER ] [ "," IDENTIFIER] ;
|
|
|
+ export = "export" [ "(" [ BUILTINTYPE | IDENTIFIER { "," literal } ] ")" ] ;
|
|
|
+ typeHint = BUILTINTYPE | IDENTIFIER ;
|
|
|
+
|
|
|
+ constDecl = "const" IDENTIFIER [ ":" typeHint ] "=" expression NEWLINE ;
|
|
|
+
|
|
|
+ signalDecl = "signal" IDENTIFIER [ signalParList ] NEWLINE ;
|
|
|
+ signalParList = "(" [ IDENTIFIER { "," IDENTIFIER } ] ")" ;
|
|
|
+
|
|
|
+ enumDecl = "enum" [ IDENTIFIER ] "{" [ IDENTIFIER [ "=" INTEGER ]
|
|
|
+ { "," IDENTIFIER [ "=" INTEGER ] } [ "," ] ] "}" NEWLINE ;
|
|
|
+
|
|
|
+ methodDecl = [ rpc ] [ "static" ] "func" IDENTIFIER "(" [ parList ] ")"
|
|
|
+ [ "->" typeHint] ":" stmtOrSuite ;
|
|
|
+ parList = parameter { "," parameter } ;
|
|
|
+ parameter = [ "var" ] IDENTIFIER [ ":" typeHint ] [ "=" expression ] ;
|
|
|
+ rpc = "remote" | "master" | "puppet"
|
|
|
+ | "remotesync" | "mastersync" | "puppetsync";
|
|
|
+
|
|
|
+ constructorDecl = "func" IDENTIFIER "(" [ parList ] ")"
|
|
|
+ [ "." "(" [ argList ] ")" ] ":" stmtOrSuite ;
|
|
|
+ argList = expression { "," expression } ;
|
|
|
+
|
|
|
+ innerClass = "class" IDENTIFIER [ inheritance ] ":" NEWLINE
|
|
|
+ INDENT [ inheritance NEWLINE ] topLevelDecl { topLevelDecl } DEDENT ;
|
|
|
+
|
|
|
+ stmtOrSuite = stmt | NEWLINE INDENT suite DEDENT ;
|
|
|
+ suite = stmt { stmt };
|
|
|
+
|
|
|
+ stmt
|
|
|
+ = varDeclStmt
|
|
|
+ | ifStmt
|
|
|
+ | forStmt
|
|
|
+ | whileStmt
|
|
|
+ | matchStmt
|
|
|
+ | flowStmt
|
|
|
+ | assignmentStmt
|
|
|
+ | exprStmt
|
|
|
+ | assertStmt
|
|
|
+ | yieldStmt
|
|
|
+ | preloadStmt
|
|
|
+ | "breakpoint" stmtEnd
|
|
|
+ | "pass" stmtEnd
|
|
|
+ ;
|
|
|
+ stmtEnd = NEWLINE | ";" ;
|
|
|
+
|
|
|
+ ifStmt = "if" expression ":" stmtOrSuite { "elif" expression ":" stmtOrSuite }
|
|
|
+ [ "else" ":" stmtOrSuite ] ;
|
|
|
+ whileStmt = "while" expression ":" stmtOrSuite;
|
|
|
+ forStmt = "for" IDENTIFIER "in" expression ":" stmtOrSuite ;
|
|
|
+
|
|
|
+ matchStmt = "match" expression ":" NEWLINE INDENT matchBlock DEDENT;
|
|
|
+ matchBlock = patternList ":" stmtOrSuite { patternList ":" stmtOrSuite };
|
|
|
+ patternList = pattern { "," pattern } ;
|
|
|
+ (* Note: you can't have a binding in a pattern list, but to not complicate the
|
|
|
+ grammar more it won't be restricted syntactically *)
|
|
|
+ pattern = literal | BUILTINTYPE | CONSTANT | "_" | bindingPattern
|
|
|
+ | arrayPattern | dictPattern ;
|
|
|
+ bindingPattern = "var" IDENTIFIER ;
|
|
|
+ arrayPattern = "[" [ pattern { "," pattern } [ ".." ] ] "]" ;
|
|
|
+ dictPattern = "{" [ keyValuePattern ] { "," keyValuePattern } [ ".." ] "}" ;
|
|
|
+ keyValuePattern = STRING [ ":" pattern ] ;
|
|
|
+
|
|
|
+ flowStmt
|
|
|
+ = "continue" stmtEnd
|
|
|
+ | "break" stmtEnd
|
|
|
+ | "return" [ expression ] stmtEnd
|
|
|
+ ;
|
|
|
+
|
|
|
+ assignmentStmt = subscription "=" expression stmtEnd;
|
|
|
+ varDeclStmt = "var" IDENTIFIER [ "=" expression ] stmtEnd;
|
|
|
+
|
|
|
+ assertStmt = "assert" "(" expression [ "," STRING ] ")" stmtEnd ;
|
|
|
+ yieldStmt = "yield" "(" [ expression "," expression ] ")" ;
|
|
|
+ preloadStmt = "preload" "(" CONSTANT ")" ;
|
|
|
+
|
|
|
+ (* This expression grammar encodes precedence. Items later in the list have
|
|
|
+ higher precedence than the ones before. *)
|
|
|
+ exprStmt = expression stmtEnd ;
|
|
|
+ expression = cast [ "[" expression "]" ] ;
|
|
|
+ cast = ternaryExpr [ "as" typeHint ];
|
|
|
+ ternaryExpr = logicOr [ "if" logicOr "else" logicOr ] ;
|
|
|
+ logicOr = logicAnd { ( "or" | "||" ) logicAnd } ;
|
|
|
+ logicAnd = logicNot { ( "and" | "&&" ) logicNot };
|
|
|
+ logicNot = ( "!" | "not" ) logicNot | in;
|
|
|
+ in = comparison { "in" comparison };
|
|
|
+ comparison = bitOr { ( "<" | ">" | "<=" | ">=" | "==" | "!=" ) bitOr } ;
|
|
|
+ bitOr = bitXor { "|" bitXor } ;
|
|
|
+ bitXor = bitAnd { "^" bitAnd } ;
|
|
|
+ bitAnd = bitShift { "&" bitShift } ;
|
|
|
+ bitShift = minus { ( "<<" | ">>" ) minus } ;
|
|
|
+ minus = plus { "-" plus } ;
|
|
|
+ plus = factor { "+" factor } ;
|
|
|
+ factor = sign { ( "*" | "/" | "%" ) sign } ;
|
|
|
+ sign = ( "-" | "+" ) sign | bitNot ;
|
|
|
+ bitNot = "~" bitNot | is ;
|
|
|
+ is = call [ "is" ( IDENTIFIER | BUILTINTYPE ) ] ;
|
|
|
+ call = attribute [ "(" [ argList ] ")" ];
|
|
|
+ attribute = subscription { "." IDENTIFIER } ;
|
|
|
+ subscription = primary [ "[" expression "]" ] ;
|
|
|
+ primary = "true" | "false" | "null" | "self" | literal | arrayDecl
|
|
|
+ | dictDecl | "(" expression ")" ;
|
|
|
+
|
|
|
+ literal = STRING | NUMBER | IDENTIFIER | BUILTINTYPE
|
|
|
+ | "PI" | "TAU" | "NAN" | "INF" ;
|
|
|
+ arrayDecl = "[" [ expression { "," expression } "," ] "]" ;
|
|
|
+ dictDecl = "{" [ keyValue { "," keyValue } "," ] "}" ;
|
|
|
+ keyValue
|
|
|
+ = expression ":" expression
|
|
|
+ | IDENTIFIER "=" expression
|
|
|
+ ;
|
Max Hilbrunner