brain 0.1.2

Compiler for the brain programming language. Compiles brain into optimized brainfuck code. Also includes a brainfuck interpreter.
Documentation 
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use parser::{Expression, Statement};
use instructions::Instructions;
use memory::MemoryLayout;

use super::errors::Error;
use super::statements::expand;
use super::input::read_input;

pub fn if_condition(
    instructions: &mut Instructions,
    mem: &mut MemoryLayout,
    condition: Expression,
    body: Vec<Statement>,
) -> Result<(), Error> {
    loop_condition(instructions, mem, &condition)?;

    instructions.jump_forward_if_zero();

    for stmt in body {
        expand(instructions, mem, stmt)?;
    }

    loop_condition(instructions, mem, &condition)?;

    instructions.jump_backward_unless_zero();

    Ok(())
}

pub fn loop_condition(
    instructions: &mut Instructions,
    mem: &mut MemoryLayout,
    condition: &Expression,
) -> Result<(), Error> {
    let size = match condition {
        &Expression::StringLiteral(_) => {
            return Err(Error::LoopStringLiteralUnsupported {});
        },
        &Expression::Identifier(ref name) => {
            let (_, size) = mem.get_cell_contents(name).ok_or_else(|| Error::UndeclaredIdentifier {name: name.clone()})?;
            size
        },
    };

    if size != 1 {
        return Err(Error::ConditionSizeInvalid {
            expected: 1,
            actual: size,
        });
    }

    Ok(())
}