Work on ast.schema and related.

src/parser/ast.schema.yaml

@@ -9,22 +9,52 @@ $defs:
     type: object
     additionalProperties: false
     description: A definition of a node type.
+    oneOf:
+      - $ref: "#/$defs/StructNodeDefinition"
+      - $ref: "#/$defs/EnumNodeDefinition"
+      - $ref: "#/$defs/LeafEnumNodeDefinition"
+  StructNodeDefinition:
+    type: object
+    additionalProperties: false
+    description: A description of a Struct node to be built.
     properties:
+      type:
+        const: struct
       children:
-        type: array
         description: Ordered child fields for this node.
         items:
           $ref: "#/$defs/StructChildDefinition"
+    required:
+      - children
+  EnumNodeDefinition:
+    type: object
+    additionalProperties: false
+    description: A description of an Enum node to be built.
+    properties:
+      type:
+        const: enum
       rules:
         type: array
         description: Alternative parse rules that build this node.
         items:
           $ref: "#/$defs/EnumChildDefinition"
-    oneOf:
-      - required:
-          - "children"
-      - required:
-          - "rules"
+    required:
+      - rules
+  LeafEnumNodeDefinition:
+    type: object
+    additionalProperties: false
+    description: A description of a leaf-enum node to be built.
+    properties:
+      type:
+        const: leaf_enum
+      rules:
+        type: array
+        description: Alternative parse rules that build this node.
+        items:
+          $ref: "#/$defs/LeafEnumChildDefinition"
+    required:
+      - type
+      - rules
   StructChildDefinition:
     description: A definition of a node's child. Either a bare child name (string) in snake case, or an object.
     oneOf:
@@ -93,6 +123,10 @@ $defs:
     oneOf:
       - $ref: "#/$defs/BuildSingleTypeChild"
       - $ref: "#/$defs/BuildBooleanChild"
+      - $ref: "#/$defs/BuildStringChild"
+      - $ref: "#/$defs/BuildDoubleChild"
+      - $ref: "#/$defs/BuildIntChild"
+      - $ref: "#/$defs/BuildLongChild"
   BuildSingleTypeChild:
     type: object
     additionalProperties: false
@@ -117,6 +151,54 @@ $defs:
         type: string
         enum:
           - rule_present
+      from:
+        type: string
+        enum: 
+          - parse_whole_pair
+  BuildStringChild:
+    type: object
+    additionalProperties: false
+    description: A definition for building a string child.
+    properties: 
+      type:
+        const: string
+      from:
+        type: string
+        enum:
+          - whole_pair
+  BuildDoubleChild:
+    type: object
+    additionalProperties: false
+    description: A definition for building a Double child.
+    properties: 
+      type:
+        const: f64
+      from:
+        type: string
+        enum:
+          - parse_whole_pair
+  BuildIntChild:
+    type: object
+    additionalProperties: false
+    description: A definition for building an Int child.
+    properties: 
+      type:
+        const: i32
+      from:
+        type: string
+        enum:
+          - parse_number_base
+  BuildLongChild:
+    type: object
+    additionalProperties: false
+    description: A definition for building a Long child.
+    properties: 
+      type:
+        const: i64
+      from:
+        type: string
+        enum:
+          - parse_number_base
   EnumChildDefinition:
     description: A definition of an enum node's child. Either a bare rule (string) in Pascal case, or an object.
     oneOf:
@@ -135,3 +217,28 @@ $defs:
     required:
       - rule
       - build
+  LeafEnumChildDefinition:
+    description: A definition of a leaf-enum node's child. Either a bare rule-string in Pascal case, or an object.
+    oneOf:
+      - type: string
+        description: Shorthand where the rule name maps onto an empty enum rule.
+      - $ref: "#/$defs/LongLeafEnumChildDefinitionWrapper"
+  LongLeafEnumChildDefinitionWrapper:
+    type: object
+    description: Single-key object mapping the child-name to its spec.
+    minProperties: 1
+    maxProperties: 1
+    additionalProperties: false
+    patternProperties:
+      "^([A-Z][a-z0-9]*)*$":
+        $ref: "#/$defs/LongLeafEnumChildDefinition"
+  LongLeafEnumChildDefinition:
+    type: object
+    additionalProperties: false
+    description: A format for specifying more specific information about a leaf-enum child.
+    properties:
+      child:
+        type: boolean
+        description: If true, a node of the same name is built as the lone member of the enum child.
+    required:
+      - child

src/parser/ast.yaml

@@ -206,3 +206,517 @@ PlatformFunction:
     - identifier
     - parameters
     - return_type
+InterfaceFunction:
+  children:
+    - fn_kw:
+        rule: Fn
+        skip: true
+    - generics:
+        rule: GenericParameters
+        build:
+          or_else_default: true
+    - identifier
+    - parameters
+    - return_type
+InterfaceDefaultFunction:
+  children:
+    - def_kw:
+        rule: Def
+        skip: true
+    - fn_kw:
+        rule: Fn
+        skip: true
+    - generics:
+        rule: GenericParameters
+        build:
+          or_else_default: true
+    - identifier
+    - parameters
+    - return_type:
+        build:
+          or_else: void
+    - function_body
+InterfaceOperatorFunction:
+  children:
+    - op_kw:
+        rule: Op
+        skip: true
+    - generics:
+        rule: GenericParameters
+        build:
+          or_else_default: true
+    - operator
+    - parameters
+    - return_type
+InterfaceDefaultOperatorFunction:
+  children:
+    - def_kw:
+        rule: Def
+        skip: true
+    - op_kw:
+        rule: Op
+        skip: true
+    - generics:
+        rule: GenericParameters
+        build:
+          or_else_default: true
+    - operator
+    - parameters
+    - return_type:
+        build:
+          or_else: void
+    - function_body
+      
+# Function Bodies
+FunctionBody:
+  rules:
+    - FunctionAliasBody
+    - FunctionEqualsBody
+    - FunctionBlockBody
+FunctionEqualsBody:
+  children:
+    - expression
+FunctionAliasBody:
+  children:
+    - alias_kw:
+        rule: Alias
+        skip: true
+    - identifier
+FunctionBlockBody:
+  children:
+    - statements:
+        rule: Statement
+        vec: true
+    - end_kw:
+        rule: End
+        skip: true
+
+# Class constructs
+ClassConstructor:
+  children:
+    - members:
+        rule: Member
+        vec: true
+Member:
+  children:
+    - is_public:
+        rule: Pub
+        build: 
+          type: boolean
+          on: rule_present
+    - is_mut:
+        rule: Mut
+        build:
+          type: boolean
+          on: rule_present
+    - identifier
+    - type_use
+
+# Statements
+Statement:
+  rules:
+    - VariableDeclaration
+    - AssignmentStatement
+    - ExpressionStatement
+    - UseStatement
+    - IfElseStatement
+    - IfStatementStatement
+    - WhileStatement
+    - ForStatement
+VariableDeclaration:
+  children:
+    - let_kw:
+        rule: Let
+        skip: true
+    - is_mut:
+        rule: Mut
+        build:
+          type: boolean
+          on: rule_present
+    - identifier
+    - type_use:
+        optional: true
+    - expression:
+        optional: true
+AssignmentStatement:
+  children:
+    - left:
+        rule: Expression
+    - right:
+        rule: Expression
+ExpressionStatement:
+  children:
+    - expression
+IfStatement:
+  children:
+    - if_clause
+    - if_else_ifs:
+        rule: IfElseIf
+        vec: true
+    - if_else
+    - end_kw:
+        rule: End
+        skip: true
+IfClause:
+  children:
+    - if_kw:
+        rule: If
+        skip: true
+    - expression
+    - then_kw:
+        rule: Then
+        skip: true
+    - statements:
+        rule: Statement
+        vec: true
+IfElseIf:
+  children:
+    - else_kw:
+        rule: Else
+        skip: true
+    - if_clause
+IfElse:
+  children:
+    - else_kw:
+        rule: Else
+        skip: true
+    - statements:
+        rule: Statement
+        vec: true
+WhileStatement:
+  children:
+    - while_kw:
+        rule: While
+        skip: true
+    - expression
+    - do_kw:
+        rule: Do
+        skip: true
+    - statements:
+        rule: Statement
+        vec: true
+    - end_kw:
+        rule: End
+        skip: true
+ForStatement:
+  children:
+    - for_kw:
+        rule: For
+        skip: true
+    - identifier
+    - in_kw:
+        rule: In
+        skip: true
+    - expression
+    - do_kw:
+        rule: Do
+        skip: true
+    - statement:
+        rule: Statement
+        vec: true
+    - end_kw:
+        rule: End
+        vec: true
+
+# Expressions
+Expression:
+  children:
+    - ternary_expression
+TernaryExpression:
+  children:
+    - or_expression
+    - ternary_alternatives:
+        optional: true
+TernaryAlternatives:
+  children:
+    - ternary_true_alternative
+    - ternary_false_alternative
+TernaryTrueAlternative:
+  children:
+    - expression
+TernaryFalseAlternative:
+  children:
+    - expression
+OrExpression:
+  children:
+    - left:
+        rule: AndExpression
+    - or_sym:
+        rule: Or
+        skip: true
+    -  right:
+         rule: Expression
+         optional: true
+AndExpression:
+  children:
+    - left:
+        rule: ComparisonExpression
+    - and_sym:
+        rule: And
+        skip: true
+    - right:
+        rule: Expression
+        optional: true
+ComparisonExpression:
+  children:
+    - left: 
+        rule: ShiftExpression
+    - operator:
+        rule: ComparisonOperator
+        optional: true
+    - right:
+        rule: Expression
+        optional: true
+ComparisonOperator:
+  rules:
+    - Greater
+    - Less
+    - GreaterEqual
+    - LessEqual
+    - EqualTo
+    - NotEqualTo
+ShiftExpression:
+  children:
+    - left:
+        rule: AdditiveExpression
+    - operator:
+        rule: ShiftOperator
+        optional: true
+    - right:
+        rule: Expression
+ShiftOperator:
+  rules:
+    - LeftShift
+    - RightShift
+AdditiveExpression:
+  children:
+    - left:
+        rule: MultiplicativeExpression
+    - operator:
+        rule: AdditiveOperator
+        optional: true
+    - right:
+        rule: Expression
+        optional: true
+MultiplicativeExpression:
+  children:
+    - left:
+        rule: PrefixExpression
+    - operator:
+        rule: MultiplicativeOperator
+        optional: true
+    - right:
+        rule: Expression
+MultiplicativeOperator:
+  type: leaf_enum
+  rules:
+    - Multiply
+    - Divide
+    - Modulo
+PrefixExpression:
+  children:
+    - operators:
+        rule: PrefixOperator
+        vec: true
+PrefixOperator:
+  type: leaf_enum
+  rules:
+    - Spread
+    - Not
+    - Negative
+SuffixExpression:
+  children:
+    - left:
+        rule: PrimaryExpression
+    - operators:
+        rule: SuffixOperator
+        vec: true
+SuffixOperator:
+  type: leaf_enum
+  rules:
+    - PlusPlus
+    - MinusMinus
+    - ObjectProperty:
+        child: true
+    - ObjectIndex:
+        child: true
+    - Call:
+        child: true
+ObjectProperty:
+  children:
+    - identifier
+ObjectIndex:
+  children:
+    - expression
+PrimaryExpression:
+  rules:
+    - Literal
+    - FullyQualifiedName
+    - Closure
+    - ParenthesizedExpression
+ParenthesizedExpression:
+  children:
+    - expression
+
+# Calls
+Call:
+  rules:
+    - ParenthesesCall
+    - NonParenthesesCall
+ParenthesesCall:
+  children:
+    - turbo_fish:
+        optional: true
+    - expression_list:
+        optional: true
+    - closure:
+        optional: true
+NonParenthesesCall:
+  children:
+    - turbo_fish:
+        optional: true
+    - expression_list:
+        optional: true
+    - closure:
+        optional: true
+TurboFish:
+  children:
+    - generic_arguments
+ExpressionList:
+  children:
+    - expressions:
+        rule: Expression
+        vec: true
+
+# Closure
+Closure:
+  children:
+    - closure_parameters:
+        build:
+          or_else_default: true
+    - statements:
+        rule: Statement
+        vec: true
+ClosureParameters:
+  children:
+    - parameters:
+        rule: ClosureParameters
+        vec: true
+ClosureParameter:
+  children:
+    - identifier
+    - type_use:
+        optional: true
+
+# Literals
+Literal:
+  rules:
+    - NumberLiteral
+    - StringLiteral
+    - BooleanLiteral
+NumberLiteral:
+  rules:
+    - DoubleLiteral
+    - LongLiteral
+    - IntLiteral
+IntLiteral:
+  children:
+    - number_base
+    - literal:
+        build:
+          type: i32
+          from: parse_number_base
+LongLiteral:
+  children:
+    - number_base
+    - literal:
+        build:
+          type: i64
+          from: parse_number_base
+DoubleLiteral:
+  children:
+    - literal:
+        build: 
+          type: f64
+          from: parse_whole_pair
+NumberBase:
+  rules:
+    - BinaryBase
+    - HexadecimalBase
+    - DecimalBase
+DecimalBase:
+  children:
+    - literal:
+        build: 
+          type: string
+          from: whole_pair
+BinaryBase:
+  children:
+    - binary_digits
+BinaryDigits:
+  children:
+    - literal:
+        build:
+          type: string
+          from: whole_pair
+HexadecimalBase:
+  children:
+    - hexadecimal_digits
+HexadecimalDigits:
+  children:
+    - literal:
+        build: 
+          type: string
+          from: whole_pair
+StringLiteral:
+  rules:
+    - SingleQuoteString
+    - DoubleQuoteString
+    - BacktickString
+SingleQuoteString:
+  children:
+    - string_inner:
+        optional: true
+DoubleQuoteString:
+  children:
+    - inners:
+        rule: DStringInner
+        vec: true
+    - expressions:
+        rule: DStringExpression
+        vec: true
+StringInner:
+  children:
+    - literal:
+        build:
+          type: string
+          from: whole_pair
+DStringInner:
+  children:
+    - literal:
+        build: 
+          type: string
+          from: whole_pair
+DStringExpression:
+  children:
+    - expression
+BacktickString:
+  children:
+    - inners:
+        rule: BacktickInner
+        vec: true
+    - expressions:
+        rule: DStringExpression
+        vec: true
+BacktickInner:
+  children:
+    - literal:
+        build: 
+          type: string
+          from: whole_pair
+BooleanLiteral:
+  children:
+    - literal:
+        build: 
+          type: boolean
+          from: parse_whole_pair

src/parser/deimos.pest

@@ -30,6 +30,8 @@ Alias = { "alias" }
 True = { "true" }
 False = { "false" }
 Use = { "use" }
+Then = { "then" }
+Do = { "do" }
 End = { "end" }
 Companion = { "comp" }
 
@@ -79,6 +81,10 @@ Keyword = {
     | True
     | False
     | Use
+    | Then
+    | Do
+    | End
+    | Companion
     | Byte
     | Short
     | Char
@@ -458,8 +464,7 @@ PlatformFunction = {
 }
 
 InterfaceFunction = {
-      FunctionModifier?
-    ~ Fn
+      Fn
     ~ GenericParameters?
     ~ Identifier
     ~ Parameters
@@ -468,18 +473,16 @@ InterfaceFunction = {
 
 InterfaceDefaultFunction = {
       Def
-    ~ FunctionModifier?
     ~ Fn
     ~ GenericParameters?
     ~ Identifier
     ~ Parameters
-    ~ ReturnType
+    ~ ReturnType?
     ~ FunctionBody
 }
 
 InterfaceOperatorFunction = {
-      FunctionModifier?
-    ~ Op
+      Op
     ~ GenericParameters?
     ~ Operator
     ~ Parameters
@@ -488,12 +491,11 @@ InterfaceOperatorFunction = {
 
 InterfaceDefaultOperatorFunction = {
       Def
-    ~ FunctionModifier?
     ~ Op
     ~ GenericParameters?
     ~ Operator
     ~ Parameters
-    ~ ReturnType
+    ~ ReturnType?
     ~ FunctionBody
 }
 
@@ -502,7 +504,7 @@ InterfaceDefaultOperatorFunction = {
 FunctionBody = {
       FunctionAliasBody
     | FunctionEqualsBody
-    | BlockStatement
+    | FunctionBlockBody
 }
 
 FunctionEqualsBody = {
@@ -515,30 +517,23 @@ FunctionAliasBody = {
     ~ Identifier
 }
 
+FunctionBlockBody = {
+      Statement*
+    ~ End
+}
+
 // Class constructs
 
 ClassConstructor = {
       "("
-    ~ DataMember
-    ~ ( "," ~ DataMember )*
+    ~ Member
+    ~ ( "," ~ Member )*
     ~ ")"
 }
 
-DataMember = {
-      Property
-    | Field
-}
-
-Property = {
-      Mut?
-    ~ Identifier
-    ~ ":"
-    ~ TypeUse
-}
-
-Field = {
-      Mut?
-    ~ Fld
+Member = {
+      Pub?
+    ~ Mut?
     ~ Identifier
     ~ ":"
     ~ TypeUse
@@ -546,29 +541,14 @@ Field = {
 
 // Statements
 
-BlockStatement = {
-      "{"
-    ~ Statement*
-    ~ Expression?
-    ~ "}"
-}
-
 Statement = {
-      (
       VariableDeclaration
     | AssignmentStatement
-        | CallStatement
-        | ReturnStatement
+    | ExpressionStatement
     | UseStatement
-      )
-    ~ Semicolon
-    | (
-          BlockStatement
-        | IfElseStatement
     | IfStatement
     | WhileStatement
     | ForStatement
-      )
 }
 
 VariableDeclaration = {
@@ -585,63 +565,50 @@ AssignmentStatement = {
     ~ Expression
 }
 
-CallStatement = { 
-      PrimaryExpression
-    ~ ObjectAccess?
-    ~ ParenthesesCall
-    ~ (
-          ObjectAccess
-        | ParenthesesCall
-        | PlusPlus
-        | MinusMinus
-      )*    
-}
-
-ReturnStatement = {
-      Return
-    ~ Expression?
+ExpressionStatement = {
+      Expression
 }
 
 IfStatement = {
+      IfClause
+    ~ IfElseIf*
+    ~ IfElse?
+    ~ End
+}
+
+IfClause = {
       If
-    ~ "("
     ~ Expression
-    ~ ")"
-    ~ BlockStatement
+    ~ Then
+    ~ Statement*
 }
 
-IfElseStatement = {
-      IfStatement
-    ~ ElseIf*
-    ~ ElseBlock?
-}
-
-ElseIf = {
+IfElseIf = {
       Else
-    ~ IfStatement
+    ~ IfClause
 }
 
-ElseBlock = {
+IfElse = {
       Else
-    ~ BlockStatement
+    ~ Statement*
 }
 
 WhileStatement = {
       While
-    ~ "("
     ~ Expression
-    ~ ")"
-    ~ BlockStatement
+    ~ Do
+    ~ Statement*
+    ~ End
 }
 
 ForStatement = {
       For
-    ~ "("
     ~ Identifier
     ~ In
     ~ Expression
-    ~ ")"
-    ~ BlockStatement
+    ~ Do
+    ~ Statement*
+    ~ End
 }
 
 // Expressions
@@ -652,12 +619,22 @@ Expression = {
 
 TernaryExpression = {
       OrExpression
-    ~ ( 
+    ~ ( TernaryAlternatives )?
+}
+
+TernaryAlternatives = {
+      TernaryTrueAlternative
+    ~ TernaryFalseAlternative
+}
+
+TernaryTrueAlternative = {
       "?"
     ~ Expression
-        ~ ":"
+}
+
+TernaryFalseAlternative = {
+      ":"
     ~ Expression
-      )?
 }
 
 OrExpression = {
@@ -673,52 +650,93 @@ AndExpression = {
 ComparisonExpression = {
       ShiftExpression
     ~ (
-          ( Greater | Less | GreaterEqual | LessEqual | EqualTo | NotEqualTo )
+          ComparisonOperator
         ~ Expression
       )?
 }
 
+ComparisonOperator = {
+      Greater
+    | Less
+    | GreaterEqual
+    | LessEqual
+    | EqualTo
+    | NotEqualTo
+}
+
 ShiftExpression = {
       AdditiveExpression
-    ~ ( ( LeftShift | RightShift ) ~ Expression )?
+    ~ (
+          ShiftOperator
+        ~ Expression
+      )?
+}
+
+ShiftOperator = {
+      LeftShift
+    | RightShift
 }
 
 AdditiveExpression = {
       MultiplicativeExpression
     ~ (
-          ( Add | Subtract )
+          AdditiveOperator
         ~ Expression
       )?
 }
 
+AdditiveOperator = {
+      Add
+    | Subtract
+}
+
 MultiplicativeExpression = {
       PrefixExpression
     ~ (
-          ( Multiply | Divide | Modulo )
+          MultiplicativeOperator
         ~ Expression
       )?
 }
 
+MultiplicativeOperator = {
+      Multiply
+    | Divide
+    | Modulo
+}
+
 PrefixExpression = {
-      ( 
+      PrefixOperator*
+    ~ SuffixExpression
+}
+
+PrefixOperator = {
       Spread
-        | BorrowMut
-        | Borrow
-        | Mut
     | Not
     | Negative
-      )*
-    ~ SuffixExpression
 }
 
 SuffixExpression = {
       PrimaryExpression
-    ~ (
-          ObjectAccess
-        | ParenthesesCall
-        | PlusPlus
+    ~ SuffixOperator*
+}
+
+SuffixOperator = {
+      PlusPlus
     | MinusMinus
-      )*
+    | ObjectProperty
+    | ObjectIndex
+    | Call
+}
+
+ObjectProperty = {
+      "."
+    ~ Identifier
+}
+
+ObjectIndex = {
+      "["
+    ~ Expression
+    ~ "]"
 }
 
 PrimaryExpression = {
@@ -734,23 +752,13 @@ ParenthesizedExpression = {
     ~ ")"
 }
 
-ObjectAccess = {
-      ( ObjectProperty | ObjectIndex )+
-}
-
-ObjectProperty = {
-      "."
-    ~ Identifier
-}
-
-ObjectIndex = {
-      "["
-    ~ Expression
-    ~ "]"
-}
-
 // Calls
 
+Call = {
+      ParenthesesCall
+    | NonParenthesesCall
+}
+
 ParenthesesCall = {
       TurboFish?
     ~ "("
@@ -759,6 +767,15 @@ ParenthesesCall = {
     ~ Closure?
 }
 
+NonParenthesesCall = {
+      TurboFish?
+    ~ (
+          Closure
+        | ExpressionList
+        | ExpressionList ~ Closure
+      )
+}
+
 TurboFish = {
       "::"
     ~ GenericArguments
@@ -772,13 +789,9 @@ ExpressionList = {
 // Closure
 
 Closure = {
-      ( Cons | Mut )?
-    ~ Move?
-    ~ ClosureCaptures?
-    ~ "{"
+      "{"
     ~ ( ClosureParameters? ~ "->" )?
     ~ Statement*
-    ~ Expression?
     ~ "}"
 }
 
@@ -792,19 +805,6 @@ ClosureParameter = {
     ~ ( ":" ~ TypeUse )?
 }
 
-ClosureCaptures = {
-      "|"
-    ~ ClosureCapture
-    ~ ( "," ~ ClosureCapture )*
-    ~ "|"
-}
-
-ClosureCapture = {
-      Borrow*
-    ~ Mut?
-    ~ Identifier
-}
-
 // Literals
 
 Literal = {
@@ -823,7 +823,7 @@ IntLiteral = { NumberBase }
 
 LongLiteral = ${ NumberBase ~ "L" }
 
-DoubleLiteral = ${ DecimalBase ~ "." ~ Digit+ }
+DoubleLiteral = @{ DecimalBase ~ "." ~ DecimalBase}
 
 NumberBase = {
       BinaryBase
@@ -831,18 +831,17 @@ NumberBase = {
     | DecimalBase
 }
 
-DecimalBase = @{
-      "0"
-    | DecimalStartDigit ~ Digit*
-}
+DecimalBase = @{ '0'..'9'+ }
 
-BinaryBase = @{ "0b" ~ Digit+ }
+BinaryBase = { "0b" ~ BinaryDigits }
 
-DecimalStartDigit = { '1'..'9' }
+BinaryDigits = @{ BinaryDigit+ }
 
-Digit = @{ '0'..'9'+ }
+BinaryDigit = { "0" | "1" }
 
-HexadecimalBase = @{ "0x" ~ HexadecimalDigit+ }
+HexadecimalBase = { "0x" ~ HexadecimalDigits }
+
+HexadecimalDigits = @{ HexadecimalDigit+ }
 
 HexadecimalDigit = { '0'..'9' | 'a'..'f' }
 
@@ -874,7 +873,7 @@ DStringInner = @{ DStringChar+ }
 DStringChar = {
       !( "\"" | "\\" | "${" ) ~ ANY
     | "\\" ~ ( "\"" | "\\" | "/" | "b" | "f" | "n" | "r" | "t" | "$" )
-    | "\\" ~ ( "u" ~ ASCII_HEX_DIGIT{4} )
+    | "\\" ~ "u" ~ ASCII_HEX_DIGIT{4}
 }
 
 DStringExpression = {
@@ -893,9 +892,9 @@ BacktickString = {
 BacktickInner = @{ BacktickStringChar+ }
 
 BacktickStringChar = {
-      !( "\\`" | "\\" | "${" ) ~ ANY
+      !( "`" | "\\" | "${" ) ~ ANY
     | "\\" ~ ( "`" | "\\" | "/" | "b" | "f" | "n" | "r" | "t" | "$" )
-    | "\\" ~ ( "u" ~ ASCII_HEX_DIGIT{4} )
+    | "\\" ~ "u" ~ ASCII_HEX_DIGIT{4}
 }
 
 BooleanLiteral = { True | False }