CS3361 Assignment 3 Fall 2020 Lexical ✓ Solved

Cs3361 Assignment 3pdfcs 3361 Fall 2020 Assignment 3 Lexical A

Cs3361 Assignment 3pdfcs 3361 Fall 2020 Assignment 3 Lexical A

Develop a lexical analyzer in C or C++ that can identify lexemes and tokens found in a source code file provided by the user. The analyzer should accept the source code file as a command line argument, process it according to the specified grammar in BNF, and output each lexeme with its associated token. Invalid lexemes should be reported with the token "UNKNOWN". The program must handle whitespace, tabs, and end-of-line characters as delimiters without reporting them as lexemes. It should display "DanC Analyzer :: R<#>" on the first line, with <#> being the specific R number, and output each lexeme/token pair on subsequent lines.

The source code is in a language called “DanC” with a defined grammar. The valid tokens include assignment operators, relational operators, keywords, identifiers, integer literals, and special symbols (parentheses, semicolons). The analyzer must match lexemes against predefined tokens, output unknown tokens for unrecognized lexemes, and ignore whitespace. It should be compatible with GNU C/C++ compiler version 5.4.0.

Sample Paper For Above instruction

The development of a lexical analyzer for the “DanC” language is a fundamental task in compiler design, serving as the initial phase in translating source code into executable programs. The core objective here is to create a program that reads a source code file, identifies lexemes based on a formal grammar provided in BNF, and outputs each lexeme along with its corresponding token. This process involves comprehensive pattern recognition capabilities, robust error handling, and adherence to specified token definitions and formatting rules.

The analyzer initiates by accepting a filename as a command line argument. If no argument is supplied or if the specified file does not exist, the program must produce an appropriate error message. Once the file is successfully loaded, the analyzer reads the input character by character, ignoring whitespace characters such as spaces, tabs, and newlines, which serve solely as delimiters. The core challenge is to parse the input stream into lexemes that match the defined language constructs.

The token definitions include keywords like `read`, `write`, `while`, and symbols such as `:=`, `=`, ``, `=`, as well as relational operators ``, and arithmetic operators `+`, `-`, `*`, `/`. Identifiers are formed from alphabetic characters possibly followed by a sequence of alphabetic or numeric characters, whereas integer literals consist of numeric sequences. Each lexeme recognized as a valid token is printed along with its token name—for example, an identifier like "i" outputs as "IDENT", an integer like "123" as "INT_LIT", and relational operators like "

Invalid lexemes, which do not correspond to any token pattern, are marked with the token "UNKNOWN" while allowing the program to continue processing subsequent input. This ensures robustness and resilience in handling unexpected or malformed input.

The parser must work seamlessly with provided source code examples, correctly recognizing tokens and handling edge cases such as unrecognized lexemes or unusual spacing. The output format begins with "DanC Analyzer :: R<#>", followed by each lexeme and its token one per line, ensuring clarity and traceability.

Efficiency and readability of code are emphasized, encouraging modular design with multiple functions dedicated to token recognition, lexeme extraction, and error handling. Clear comments and proper indentation improve maintainability and understanding. The solution should be tested in a Linux environment using the GNU C/C++ compiler (gcc g++). Additionally, a Makefile should facilitate compilation and cleaning of build artifacts, producing an executable named `danc_analyzer`.

In conclusion, designing this lexical analyzer involves translating formal grammar into a reliable and efficient C/C++ program that accurately performs tokenization of the DanC source code, providing clear output for further compilation stages.

References

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