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Simplify some grammar constructs. #247

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Simplify some grammar constructs. #247

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0a6e5cf
Simplify some grammar constructs.
dj2 Aug 25, 2024
4c57146
Fold function_prototype into function_definition
dj2 Sep 14, 2024
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92 changes: 30 additions & 62 deletions chapters/grammar.adoc
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Original file line number Diff line number Diff line change
Expand Up @@ -100,11 +100,9 @@ endif::GLSL[]

[role="bnf"]
--
_variable_identifier_ : ::
_IDENTIFIER_

_primary_expression_ : ::
_variable_identifier_ +
_IDENTIFIER_ +
_INTCONSTANT_ +
_UINTCONSTANT_ +
_FLOATCONSTANT_ +
Expand All @@ -116,7 +114,7 @@ endif::GLSL[]

_postfix_expression_ : ::
_primary_expression_ +
_postfix_expression_ _LEFT_BRACKET_ _integer_expression_ _RIGHT_BRACKET_ +
_postfix_expression_ _LEFT_BRACKET_ _expression_ _RIGHT_BRACKET_ +
_function_call_ +
_postfix_expression_ _DOT_ _FIELD_SELECTION_ +
_postfix_expression_ _INC_OP_ +
Expand All @@ -128,16 +126,7 @@ FIELD_SELECTION includes members in structures, component selection for
vectors and the 'length' identifier for the length() method
====

_integer_expression_ : ::
_expression_

_function_call_ : ::
_function_call_or_method_

_function_call_or_method_ : ::
_function_call_generic_

_function_call_generic_ : ::
_function_call_header_with_parameters_ _RIGHT_PAREN_ +
_function_call_header_no_parameters_ _RIGHT_PAREN_

Expand All @@ -152,6 +141,25 @@ _function_call_header_with_parameters_ : ::
_function_call_header_ : ::
_function_identifier_ _LEFT_PAREN_

_function_definition_ : ::
_function_declarator_ _RIGHT_PAREN_ _compound_statement_no_new_scope_

_function_identifier_ : ::
_type_specifier_ +
_postfix_expression_

_function_declarator_ : ::
_function_header_ +
_function_header_with_parameters_

_function_header_with_parameters_ : ::
_function_header_ _parameter_declaration_ +
_function_header_with_parameters_ _COMMA_ _parameter_declaration_

_function_header_ : ::
_fully_specified_type_ _IDENTIFIER_ _LEFT_PAREN_


[NOTE]
====
Grammar Note: Constructors look like functions, but lexical analysis
Expand All @@ -171,10 +179,6 @@ _postfix_expression_.
endif::ESSL[]
====

_function_identifier_ : ::
_type_specifier_ +
_postfix_expression_

_unary_expression_ : ::
_postfix_expression_ +
_INC_OP_ _unary_expression_ +
Expand Down Expand Up @@ -276,11 +280,8 @@ _expression_ : ::
_assignment_expression_ +
_expression_ _COMMA_ _assignment_expression_

_constant_expression_ : ::
_conditional_expression_

_declaration_ : ::
_function_prototype_ _SEMICOLON_ +
_function_declarator_ _RIGHT_PAREN_ _SEMICOLON_ +
_init_declarator_list_ _SEMICOLON_ +
_PRECISION_ _precision_qualifier_ _type_specifier_ _SEMICOLON_ +
_type_qualifier_ _IDENTIFIER_ _LEFT_BRACE_ _struct_declaration_list_
Expand All @@ -297,31 +298,14 @@ _identifier_list_ : ::
_COMMA_ _IDENTIFIER_ +
_identifier_list_ _COMMA_ _IDENTIFIER_

_function_prototype_ : ::
_function_declarator_ _RIGHT_PAREN_

Comment on lines -300 to -302
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I've made a different change to remove this annoying rule in #252. We do need to keep function_prototype (it's referred to in function_definition, above), but if we structure it properly then this step isn't needed at all.

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Ah, good catch, I'd missed that one earlier because function_definition was weirdly at the end of the grammar instead of with the other functions.

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I merged it into function_defintion to keep this Cl correct, but either way these rules are very confusing to read.

_function_declarator_ : ::
_function_header_ +
_function_header_with_parameters_

_function_header_with_parameters_ : ::
_function_header_ _parameter_declaration_ +
_function_header_with_parameters_ _COMMA_ _parameter_declaration_

_function_header_ : ::
_fully_specified_type_ _IDENTIFIER_ _LEFT_PAREN_

_parameter_declarator_ : ::
_type_specifier_ _IDENTIFIER_ +
_type_specifier_ _IDENTIFIER_ _array_specifier_

_parameter_declaration_ : ::
_type_qualifier_ _parameter_declarator_ +
_parameter_declarator_ +
_type_qualifier_ _parameter_type_specifier_ +
_parameter_type_specifier_

_parameter_type_specifier_ : ::
_type_qualifier_ _type_specifier_ +
_type_specifier_

_init_declarator_list_ : ::
Expand Down Expand Up @@ -349,9 +333,6 @@ _fully_specified_type_ : ::
_type_specifier_ +
_type_qualifier_ _type_specifier_

_invariant_qualifier_ : ::
_INVARIANT_

_interpolation_qualifier_ : ::
_SMOOTH_ +
ifdef::GLSL[]
Expand All @@ -362,38 +343,32 @@ ifdef::ESSL[]
_FLAT_
endif::ESSL[]

_layout_qualifier_ : ::
_LAYOUT_ _LEFT_PAREN_ _layout_qualifier_id_list_ _RIGHT_PAREN_

_layout_qualifier_id_list_ : ::
_layout_qualifier_id_ +
_layout_qualifier_id_list_ _COMMA_ _layout_qualifier_id_

_layout_qualifier_id_ : ::
_IDENTIFIER_ +
ifdef::GLSL[]
_IDENTIFIER_ _EQUAL_ _constant_expression_ +
_IDENTIFIER_ _EQUAL_ __conditional_expression__ +
endif::GLSL[]
ifdef::ESSL[]
_IDENTIFIER_ _EQUAL_ _INTCONSTANT_ +
_IDENTIFIER_ _EQUAL_ _UINTCONSTANT_ +
endif::ESSL[]
_SHARED_

_precise_qualifier_ : ::
_PRECISE_

_type_qualifier_ : ::
_single_type_qualifier_ +
_type_qualifier_ _single_type_qualifier_

_single_type_qualifier_ : ::
_storage_qualifier_ +
_layout_qualifier_ +
_LAYOUT_ _LEFT_PAREN_ _layout_qualifier_id_list_ _RIGHT_PAREN_ +
_precision_qualifier_ +
_interpolation_qualifier_ +
_invariant_qualifier_ +
_precise_qualifier_
_INVARIANT_ +
_PRECISE_

_storage_qualifier_ : ::
_CONST_ +
Expand Down Expand Up @@ -574,8 +549,7 @@ _precision_qualifier_ : ::
_LOW_PRECISION_

_struct_specifier_ : ::
_STRUCT_ _IDENTIFIER_ _LEFT_BRACE_ _struct_declaration_list_
_RIGHT_BRACE_ +
_STRUCT_ _IDENTIFIER_ _LEFT_BRACE_ _struct_declaration_list_ _RIGHT_BRACE_ +
_STRUCT_ _LEFT_BRACE_ _struct_declaration_list_ _RIGHT_BRACE_

_struct_declaration_list_ : ::
Expand Down Expand Up @@ -608,9 +582,6 @@ ifdef::ESSL[]
_assignment_expression_
endif::ESSL[]

_declaration_statement_ : ::
_declaration_

_statement_ : ::
_compound_statement_ +
_simple_statement_
Expand All @@ -621,7 +592,7 @@ Grammar Note: labeled statements for SWITCH only; 'goto' is not supported.
====

_simple_statement_ : ::
_declaration_statement_ +
_declaration_ +
_expression_statement_ +
_selection_statement_ +
_switch_statement_ +
Expand Down Expand Up @@ -682,7 +653,7 @@ _iteration_statement_ : ::

_for_init_statement_ : ::
_expression_statement_ +
_declaration_statement_
_declaration_

_conditionopt_ : ::
/* _empty_ */ +
Expand Down Expand Up @@ -719,9 +690,6 @@ ifdef::ESSL[]
_declaration_
endif::ESSL[]

_function_definition_ : ::
_function_prototype_ _compound_statement_no_new_scope_

--

In general the above grammar describes a super set of the {slname}.
Expand Down