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pl:prolog:pllib:parser_pascal [2019/06/27 15:50] (aktualna) |
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| + | ====== Parser pascal ====== | ||
| + | {{tag>parser DCG}} | ||
| + | ===== Description ===== | ||
| + | Parsing the declarative part of a Pascal block | ||
| + | |||
| + | **Source**: The Art of Prolog | ||
| + | ===== Download ===== | ||
| + | Program source code: {{parser_pascal.pl}} | ||
| + | ===== Listing ===== | ||
| + | <code prolog> | ||
| + | /* | ||
| + | The grammar for the declarative part of a Pascal program. | ||
| + | */ | ||
| + | declarative_part --> | ||
| + | const_declaration, type_declaration, | ||
| + | var_declaration, procedure_declaration. | ||
| + | |||
| + | % Constant declarations | ||
| + | |||
| + | const_declaration --> [ ]. | ||
| + | const_declaration --> | ||
| + | [const], const_definition, [;], const_definitions. | ||
| + | |||
| + | const_definitions --> [ ]. | ||
| + | const_definitions --> | ||
| + | const_definition, [;], const_definitions. | ||
| + | |||
| + | const_definition --> identifier, [=], constant. | ||
| + | |||
| + | identifier --> [X], {atom(X)}. | ||
| + | |||
| + | constant --> [X], {constant(X)}. | ||
| + | |||
| + | % Type declarations | ||
| + | |||
| + | type_declaration --> [ ]. | ||
| + | type_declaration --> | ||
| + | [type], type_definition, [;], type_definitions. | ||
| + | |||
| + | type_definitions --> [ ]. | ||
| + | type_definitions --> type_definition, [;], type_definitions. | ||
| + | |||
| + | type_definition --> identifier, [=], type. | ||
| + | |||
| + | type --> ['INTEGER']. | ||
| + | type --> ['REAL']. | ||
| + | type --> ['BOOLEAN']. | ||
| + | type --> ['CHAR']. | ||
| + | |||
| + | % Variable declarations | ||
| + | |||
| + | var_declaration --> [ ]. | ||
| + | var_declaration --> | ||
| + | [var], var_definition, [;], var_definitions. | ||
| + | |||
| + | var_definitions --> [ ]. | ||
| + | var_definitions --> var_definition, [;], var_definitions. | ||
| + | var_definition --> identifiers, [:], type. | ||
| + | |||
| + | identifiers --> identifier. | ||
| + | identifiers --> identifier, [,], identifiers. | ||
| + | |||
| + | % Procedure declarations | ||
| + | |||
| + | procedure_declaration --> [ ]. | ||
| + | procedure_declaration --> procedure_heading, [;], block. | ||
| + | |||
| + | procedure_heading --> | ||
| + | [procedure], identifier, formal_parameter_part. | ||
| + | |||
| + | formal_parameter_part --> [ ]. | ||
| + | formal_parameter_part --> ['('], formal_parameter_section, [')']. | ||
| + | |||
| + | formal_parameter_section --> formal_parameters. | ||
| + | formal_parameter_section --> | ||
| + | formal_parameters, [;], formal_parameter_section. | ||
| + | |||
| + | formal_parameters --> value_parameters. | ||
| + | |||
| + | formal_parameters --> variable_parameters. | ||
| + | |||
| + | value_parameters --> var_definition. | ||
| + | |||
| + | variable_parameters --> [var], var_definition. | ||
| + | |||
| + | % Program 19.3: Parsing the declarative part of a Pascal block | ||
| + | </code> | ||
| + | ===== Comments ===== | ||
