myPreCompiler

A modular, robust, and efficient C source code preprocessor written in C.
myPreCompiler simulates core preprocessing stages of a real compiler: it expands #include directives, removes comments, validates identifiers, and produces a transformed output with optional detailed statistics and error reports.

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Features

• Recursive #include Expansion: Supports nested and transitive inclusion of files.
• Comment Removal: Eliminates both inline (//) and multiline (/* ... */) comments using regex, preserving line numbering.
• Identifier Validation: Checks local and global variable names, logging invalid ones (e.g., illegal characters, starting with digits).
• Configurable Output: Writes processed code to a file or stdout, based on CLI options.
• Verbose Mode: Prints detailed statistics: removed lines, included files, identifiers checked, errors, and file size/line counts.
• Robust Error Handling: Detects and reports invalid CLI parameters, missing or unreadable files, unresolved or recursive includes, write errors, and more.
• Dynamic Memory Management: Efficiently processes files of arbitrary size and guarantees no memory leaks.

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Architecture

• main.c – CLI argument parsing, control flow, orchestration
• preprocessor.c – Core logic: includes, comment removal, identifier analysis
• utils.c – File handling, line parsing, logging, syntax checks
• myPreCompiler.h – Shared data structures, function prototypes, and macros

Each module communicates strictly through the header interface, ensuring low coupling and high cohesion.

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Build

To compile the project, run:

gcc src/main.c src/preprocessor.c src/utils.c -Iinclude -o myPreCompiler.out

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Usage

./myPreCompiler.out -i <input_file> [-o <output_file>] [-v]

Options:

• -i <input_file>: Input C source file to preprocess
• -o <output_file>: Output file (optional, defaults to stdout)
• -v: Verbose mode - prints detailed statistics

Examples:

Basic preprocessing

./myPreCompiler.out -i source.c -o processed.c

Verbose output to stdout

./myPreCompiler.out -i source.c -v

Process with statistics

./myPreCompiler.out -i main.c -o main_processed.c -v

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Processing Pipeline

1. Argument Parsing: Recognition and validation of CLI options (--in, --out, --verbose)
2. Include Expansion: Recursive inclusion of file contents, assumed to be in the working directory
3. Comment Removal: Elimination of inline (//) and multiline (/* */) comments via regex, maintaining original line numbering
4. Identifier Validation: Lexical checking of local and global declarations, logging invalid identifiers
5. Output Generation: Writing transformed code to file or stdout based on options
6. Statistics (Optional): In verbose mode, tracks: removed lines, included files, checked variables, identified errors, input/output file size and line counts

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Testing

Navigate to the test directory and run the test cases:

cd test

Test 1: Comment removal

../myPreCompiler.out -i test_comments.c -v -o test_comments_processed.c

Test 2: Identifier validation

../myPreCompiler.out -i test_identifiers.c -v -o test_identifiers_processed.c

Test 3: Include expansion

../myPreCompiler.out -i test_include_main.c -v -o test_include_processed.c

Test 4: Malformed include handling

../myPreCompiler.out -i test_malformed_include.c -v -o test_malformed_processed.c

Test 5: General preprocessing

../myPreCompiler.out -i test2.c -v -o test2_processed.c

Verify output integrity

diff original_file.c processed_file.c

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Data Structures and Memory Management

• Dynamic Allocation: Text I/O functions use dynamic allocation to handle files of arbitrary size
• Resizable Buffers: Strings are read line-by-line using resizable buffers
• Dynamic Arrays: Lists of errors, included files, and analyzed variables are managed via dynamic arrays
• LIFO Deallocation: Memory is explicitly deallocated at the end of processing or on fatal errors using LIFO scheme, ensuring no memory leaks

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Error Handling

The system handles:

• CLI syntax errors
• Non-existent or unreadable files
• Unresolved or recursive includes
• Corrupted or empty files
• Output write errors

All errors are redirected to stderr and the program exits with EXIT_FAILURE.

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Validation

The system has been validated through comprehensive test cases:

• test_comments.c: Verifies correct removal of single and multiline comments
• test_identifiers.c: Identifies variables with invalid syntax
• test_include_main.c, test_include_header.h: Direct and transitive inclusion
• test_malformed_include.c: Robust handling of malformed or missing include directives

Output is compared with originals using diff, and statistics are inspected for consistency.