Parsing the source file
To initialize your record wrapper class to represent the external function's parameters, you must parse the C header file, or COBOL copybook file that declares the data types used by the function.
To parse an external function source file, use the parseFile: class method of the AbtCLangParser class or the AbtCOBOLLangParser class. The parseFile: method takes the source file name as input and returns an object table (AbtCObjectTable or AbtCOBOLObjectTable which are subclasses of AbtObjectTable) containing information about the function and type definitions in the source file.
The parser runs faster if you suppress the informational and warning messages that are displayed in the System Transcript window. To suppress the messages select and run the following statements:
AbtCLangParser messageLevel: 0.
AbtCOBOLLangParser messageLevel: 0.
The parser will also run much faster if your C header or COBOL copybook file only contains the definitions it needs. If your file includes toolkit or compiler files, it will take much longer to parse.
After the source file is parsed, the object table contains an entry for each of the data types and functions defined in the file. For C, this includes the following:
• Data types defined with typedef
• Structures
• Function prototypes
• Constants defined with #define
For COBOL, this includes the following:
• 01-level declarations
• 77-level declarations
• PROCEDURE DIVISION and ENTRY statements
• Constants stored in 78-level and 88-level declarations
The interface information must be extracted from the object table and used to generate the appropriate getter and setter selectors for the fields of the structure. You can use the generateAllFieldsFrom:inClass: method of the AbtRecordGenerator class to generate the getter and setter selectors for all of the fields in the structure. Alternatively, you can use the generateFields:from:inClass: method to generate getter and setter selectors for a subset of the fields in the structure.
To generate the getter and setter selectors for the record wrappers created for the sample, enter the following code in a workspace, select it, and run it.
Parsing the C sample files
For the C sample header (.H) file, enter the following code:
"Parse the C header file and initialize the OSObject subclass.
This assumes that the OSObject subclass SampleCATMStruct has
already been created. AbtRecordGenerator adds the specified
getter and setter selectors to the class."
| anObjectTable |
anObjectTable := AbtCLangParser parseFile: 'catm.h'.
AbtRecordGenerator new
generateAllFieldsFrom: (anObjectTable dataStructures
at: 'ATM_CUSTOMER' asSmalltalkGlobalIdentifier)
inClass: SampleCATMStruct.
Parsing the COBOL sample files
For the COBOL sample copybook, enter the following code:
"Parse the COBOL cpy file and initialize the OSObject subclass.
This assumes that the OSObject subclass SampleCOBOLATMStruct has
already been created. AbtRecordGenerator adds the specified
getter and setter selectors to the class."
| anObjectTable |
anObjectTable := AbtCOBOLLangParser parseFile: 'atm.cpy'.
AbtRecordGenerator new
generateAllFieldsFrom: (anObjectTable cobol01s
at: 'ATM-CUSTOMER' asSmalltalkGlobalIdentifier)
inClass: SampleCOBOLATMStruct.
If any errors occur during processing, an error message appears in the System Transcript window.
Note:
If your source file contains C #include directives or COBOL COPY statements, the specified files will also be parsed. If those files are not in the current working directory, you must set the environment variable INCLUDE (for C) or COBCPY (for COBOL), indicating where the additional files are located.
The record wrapper class you created now includes the getter and setter methods for each of the fields in the structure. Open a Class Browser on the record wrapper class you just created (SampleCATMStruct or SampleCOBOLATMStruct) and you will see the getter and setter methods that were generated.
Selectors are not generated for nested arrays of complex types.
Performing code page conversion
When using a record structure that has been created on another platform, which most often occurs with communications parts, AbtForeignOSObject provides you with the capability to convert the information in the record structure to the proper code page. Send the message codePage: to the record structure to set the proper values for the code page for the platform on which the structure's information will be accessed, and send the message bigEndian: to indicate whether the platform on which the information will be accessed reads bytes from the "big end":
aRecordStructure codePage: 37; bigEndian: true
Note:
If you are using a record that supports both IBM 370 SAA COBOL and MicroFocus COBOL, send the object table the forHostCobolSystem message when working with IBM 370 SAA COBOL, or the forLocalCobolSystem message when working with MicroFocus COBOL.
Last modified date: 05/15/2020