Trusted Components Reuse, Contracts and Patterns Prof. Dr. Bertrand - - PowerPoint PPT Presentation

Trusted Components: Reuse, Contracts and Patterns - Lecture 21

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Trusted Components

Reuse, Contracts and Patterns

• Prof. Dr. Bertrand Meyer

Till G. Bay

Trusted Components: Reuse, Contracts and Patterns - Lecture 21

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Lecture 21: Eiffel AST

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Closing in on the AST

Use Gobo from

$eiffelstudio\ free_add_ons\ gobo\

You start from an ACE-file that you parse with Gobo’s LACE parser

$GOBO\ library\ tools\ lace\ parser\ et_lace_parser.e

Doing this will get you a universe

$GOBO\ library\ tools\ eiffel\ ast\ misc\ et_universe.e

The universe gives you access to the list of clusters in the project -> you don’t have the list of classes yet

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Building the AST

To get the list of classes call parse_all of class ET_UNIVERSE Now we can start adding class members to the AST NOTE: The AST is built using lists that match exactly the size of the parsed classes therefore if you want to add a new inheritance clause for example you will have to create a new parents list, fill it with the existing parents, add the new ones and then replace the old parent list with this new

• ne.

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Writing the AST to a File

Create an ET_DECORATED_AST_FACTORY to write the AST to a file using the ET_AST_PRINTER. This makes sure that the formatting of the class text will be preserved, whereas with ET_AST_FACTORY it wouldn’t.

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(f)AST Example

Take a look at class GELINT ($GOBO\ src\ gelint\ gelint.e) The feature execute is intresting:

a_filename: STRING a_file: KL_TEXT_INPUT_FILE a_lace_parser: ET_LACE_PARSER a_lace_error_handler: ET_LACE_E… a_universe: ET_UNIVERSE create a_file.make (a_filename) a_file.open_read if a_file.is_open_read then create a_lace_error_handler.make_standard create a_lace_parser.make (a_lace_error_handler) a_lace_parser.parse_file (a_file) a_file.close if not a_lace_parser.syntax_error then a_universe := a_lace_parser.last_universe end if a_universe /= Void then process_universe (a_universe) end else std.error.put_string ("gelint: cannot read %'") std.error.put_string (a_filename) std.error.put_line ("%'") end

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(f)AST Example: Parsing Comments too

Take a look at process_universe: This makes sure we get a ET_DECORATED_AST_FACTORY instead of a ET_AST_FACTORY. Do this before calling parse_all

• n the universe.

an_ast_factory: ET_DECORATED_AST_FACTORY create an_ast_factory.make an_ast_factory.set_keep_all_breaks (True) a_universe.set_ast_factory (an_ast_factory)

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(f)AST Example: Setting up a Universe

Still before parsing the universe, we have to set some options. If you use EiffelStudio 5.5 -> Void is a keyword with EiffelStudio 5.4 it isn’t. Do set the options correctly.

a_universe.error_handler.set_ise a_universe.error_handler.set_info_null a_universe.set_use_assign_keyword (False) a_universe.set_use_attribute_keyword (False) a_universe.set_use_convert_keyword (True) a_universe.set_use_recast_keyword (False) a_universe.set_use_reference_keyword (True) a_universe.set_use_void_keyword (True)

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(f)AST Example: Processing a universe

Go back to process_universe, instead of calling compile, call Now you can access the AST using the lists. Don’t forget that the lists need to be replaced wherever you change something $GOBO\ library\ tools\ eiffel\ ast

a_universe.activate_processors a_universe.parse_all

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(p)AST Example: Printing to a File

Where a_printer is an ET_AST_PRINTER

• ut_file: KL_TEXT_OUTPUT_FILE

create out_file.make (out_filename)

• ut_file.recursive_open_write

if out_file.is_open_write then create a_printer.make (out_file, a_universe) else create a_printer.make_null (a_universe) report_cannot_write_error (out_filename) Exceptions.die (1) end

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(p)AST Example: Printing to a File

a_cursor: DS_HASH_TABLE_CURSOR [ET_CLASS, ET_CLASS_NAME] a_class: ET_CLASS a_file: KL_TEXT_INPUT_FILE a_cursor := a_universe.classes.new_cursor from a_cursor.start until a_cursor.after loop a_class := a_cursor.item if a_class.is_preparsed then create a_file.make (a_class.filename) a_file.open_write if a_file.is_open_write then a_printer.set_file (a_file) a_class.process (a_printer) a_printer.set_null_file a_file.close else

• - Report error.

end end a_cursor.forth end

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Exam

Nature: Oral or Written Date:

• 2. February 2004 Times to be announced

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Examined Topics

Software Quality Software Components Software Reliability Reuse, Trusted Components Design Patterns Formal Methods Design by Contract Contract Based Testing Axiomatic Semantics

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Topics not Examined

Eclipse Component Model (Erich Gamma’s lecture) Abstract State Machines (Egon Börger’s lectures)

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End of lecture 21