CourseBrowserImproved

Allows user to browse all UBC courses from the command line without internet connection. Course data matches that on the SSC and includes information about pre-requisites, co-requisites, and course codes/descriptions. Information is stored locally in a B-tree. To make this project, I created a domain specific language to handle user input, and wrote a tree-walk interpreter to execute the DSL. The DSL which allows SQL-like SELECT statements, and various imperative programming constructs as described below. CourseBrowserImproved can be used as course-planning tool adjunct to the SSC.

Getting Started

Prerequisites

Requires Python 2.7. Has small incompatibilities with Python 3 (i.e. print and raw_input).

Setup

Download all files into same directory, keeping folder structure. Run python setup.py. This should take about 5 to 15 minutes to run, and requires an internet connection. This setup should only be run once, when you first install everything.

Usage

Run python main.py to access REPL, or run python main.py example.cbql to run program example.cbql.

Valid Commands:

See grammar.ebnf for full description of forms that valid commands can take, and sample.cbql for some examples. The following commands are useful for getting started:

• SELECT statements (based off SQL SELECT statements):
  • syntax: SELECT FROM [WHERE ]
  • e.g. SELECT title FROM Courses WHERE "Calculus" < description
• variables:
  • syntax: <var_name> :=
  • e.g. best_dept := "MATH"
• function definitions:
  • syntax: DEFUN : ->
  • e.g. DEFUN postreqs : n -> SELECT title FROM Courses WHERE n < prereqs
• function calls:
  • syntax: f(arg1, arg2, ... , argN)
  • e.g. get("MATH 443")
• control flow:
  • ternary operator:
    • syntax: <cond> ? <val1> : <val2>
    • e.g. DEFUN fact : n -> n = 0 ? 1 : fact(n-1)*n
  • WHILE loops:
    • syntax: WHILE <cond> : <expr>
    • e.g. DEFUN fact : n -> BEGIN x := 1; WHILE n <> 0 : BEGIN x *= n; n -= 1; END; x; END;
• operators:
  • supports +, -, * for INT, ||, <, > (STR concat and contains) for STR, !, &, | for BOOL, and =, <> (equality and inequality for all types).
• builtin functions (e.g. get, postreqs):
  • get(course_name): returns all info for course with given course_name.
  • postreqs(course_name): returns title of all courses with course_name as a prereq.
  • search(query): returns all courses with query in title or description.