minicalc

A simple interpreter for calculation of arithmetic expressions. It will start be developing from these twitch streams, but the idea is adding more features over time.

Features

Programs are:

• print E where E is an expression.
• Expressions can be: E ::= (E + E) | (E * E). Example: print (4 + (3 * 2)).
• Variables can be declared and used in expressions.
• Which variable, a sequence of characters starting by a letter, is an <identifier>.
• Operator precedence.

Notes

INPUT -> LEXICAL ANALYSIS (front-end) -> SYNTAX ANALYSIS (back-end) -> OUTPUT

The Lexical analysis will read the input and try to understand what the program does. While the Syntax analysis uses this information to create the resulting program. In this case, using Rust, it'll generate the machine code.

example:                    (treewalk)
4 + 3 * 2 =>             +
                       /   \
                      4     *
                           /  \
                          3    2

The first step will build a abstract syntax tree from the input. It's common for us to break this step into two: lexical analysis and syntactic analysics.

input -> lexical analysis -> syntactic analysis -> abstract syntax tree

Input is text file, a set of characters. The Lexical analysis will generate tokens of this text. Grouping the rules of each language. This process is called Tokenizer.

example:
if (tolerancy < 0.5)
|  |  |- identifier
|  |
|  |- parenthesis
|
|- reserved word