CSVQL: CSV Query Language

COMP2212: Programming Language Concepts

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Contents

• Introduction
  • Task Description
  • Language Definition
• Running The Application
• Compilation Guide
• Editing Lexer and Parser (Syntax and Grammer)

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Introduction

Task Description

• Design a programming langauage that supports the querying of CSV text files, and write an interpreter that is able to execute programs written in this language, using Haskell.

Language Definition

• The programming language developed is known as CSVQL, and is heavily influenced by SQL.
• A detailed description of the CSVQL programming language (including syntax, grammar, language semantics, execution model and example programs) is provided in Documentation.pdf.

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Running The Application

• Running the application involves passing an input program into the interpreter for it to execute.

• The interpreter is pre-compiled as a program called csvql, and can be found in the build directory of the repo.

• Write a program using the programming-langauge (see Documentation) and save it into a plain text file (file extension is not important) in the same directory as the language interpreter - make sure any files (i.e., .csv files) are also in the same directory.

• Execute the written program with the following command:

  • ./csvql <program name>

  • Where program name is the name of the file containing the program written in the CSVQL programming langauge.

• The result of the program will be outputted to the terminal.

• Note: Some text output from the interpreter is displayed in different colours (e.g., red for error messages). Contained within /build is a version of the interpreter (csvql-no-color) that will output results with no such colour formatting applied to the text.

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Compilation Guide

• The provided csvql.cabal file can be used with the cabal framework for compilation of the CSVQL interpreter.

• Use the following command to compile the interpreter:

cabal build

• This will create a new directory called dist-newstyle and place the compiled csvql interpreter inside it.

  • Path to the executable: dist-newstyle/build/x86_64-osx/ghc-8.4.3/csvql-0.1.0.0/x/csvql/build/csvql

• cabal can also be used to run the compiled interpreter with the following command:

cabal run csvql <programName>

• Where:
  • programName is the name of the CSVQL program being executed.
• Note however that using the cabal run command will output the version status of cabal (e.g., Up To Date) before outputting the result of the execution.

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Editing Lexer and Parser (Syntax and Grammer)

• The Haskell tools Alex and Happy were used to create the interpreter's lexer and parser respectively.
• The configuration files used for these tools can be found within /raw.
  • Tokens.x is the configuration file for Alex.
  • Grammar.y is the configuration file for Happy.
• Tokens.x can be re-compiled with:

alex Tokens.x

• This will produce a Haskell file Tokens.hs.
• Grammar.y can be re-compiled with:

alex Grammar.y

• This will produce a Haskell file Grammar.hs.
• In order to compile Grammar.y, the Tokens.hs file must be present.

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