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A01 Aleksandr Shefer #1212

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A01 Aleksandr Shefer #1212

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26 changes: 25 additions & 1 deletion src/Expr.lama
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,30 @@ import State;
-- Const (int) |
-- Binop (string, expr, expr)

public fun evalOp (op, left, right) {
case op of
"+" -> left + right
| "-" -> left - right
| "*" -> left * right
| "/" -> left / right
| "%" -> left % right
| "<" -> left < right
| ">" -> left > right
| "<=" -> left <= right
| ">=" -> left >= right
| "==" -> left == right
| "!=" -> left != right
| "&&" -> left && right
| "!!" -> left !! right
| o -> failure ("incorrect op\n")
esac
}

public fun evalExpr (st, expr) {
failure ("evalExpr not implemented\n")
case expr of
Var (s) -> st (s)
| Const (x) -> x
| Binop (op, left, right) -> evalOp(op, (evalExpr(st, left)), (evalExpr(st, right)))
| e -> failure ("incorrect expr\n")
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failure("... %s ...", expr.string) or do not do it at all (then you will receive match failure with the object that was unmatched). In future it will be easier to establish forgotten case

esac
}
33 changes: 30 additions & 3 deletions src/SM.lama
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Expand Up @@ -26,8 +26,23 @@ public fun showSM (prg) {

-- Stack machine interpreter. Takes an SM-configuration and a program,
-- returns a final configuration

fun evalInsn (c@[stack, state, world], insn) {
case insn of
ST (x) -> case stack of (z : s) -> [s, state <- [x, z], world] esac
| LD (x) -> [state(x) : stack, state, world]
| CONST (x) -> [x : stack, state, world]
| BINOP (op) -> case stack of (y : (x : s)) -> [evalOp(op, x, y) : s, state, world] esac
| READ -> case readWorld(world) of [res, newWorld] -> [res : stack, state, newWorld] esac
| WRITE -> case stack of (z : s) -> [s, state, writeWorld(z, world)] esac
esac
}

fun eval (c, insns) {
failure ("SM eval not implemented\n")
case insns of
{} -> c
| i : rest -> eval (evalInsn(c, i), rest)
esac
}

-- Runs a stack machine for a given input and a given program, returns an output
Expand All @@ -38,12 +53,24 @@ public fun evalSM (input, insns) {
-- Compiles an expression into a stack machine code.
-- Takes an expression, returns a list of stack machine instructions
fun compileExpr (expr) {
failure ("compileExpr not implemented\n")
case expr of
Var (x) -> {LD (x)}
| Const (x) -> {CONST (x)}
| Binop (op, left, right) -> compileExpr(left) +++ compileExpr(right) +++ {BINOP(op)}
| e -> failure ("incorrect expr (compileExpr)\n")
esac
}

-- Compiles a statement into a stack machine code.
-- Takes a statement, returns a list of stack machine
-- instructions.
public fun compileSM (stmt) {
failure ("compileSM not implemented\n")
case stmt of
Assn (x, expr) -> compileExpr(expr) +++ {ST (x)}
| Seq (stmt1, stmt2) -> compileSM(stmt1) +++ compileSM(stmt2)
| Read (x) -> {READ} +++ {ST (x)}
| Write (expr) -> compileExpr(expr) +++ {WRITE}
| Skip -> {}
| s -> failure ("incorrect stmt (compileSM)\n")
esac
}
11 changes: 9 additions & 2 deletions src/Stmt.lama
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Expand Up @@ -16,8 +16,15 @@ import World;
-- Read (string) |
-- Write (expr) |

fun eval (c, stmt) {
failure ("Stmt eval not implemented\n")
fun eval (c@[state, world], stmt) {
case stmt of
Assn (x, expr) -> [state <- [x, evalExpr(state, expr)], world]
| Seq (stmt1, stmt2) -> eval(eval(c, stmt1), stmt2)
| Read (x) -> case readWorld(world) of [res, newWorld] -> [state <- [x, res], newWorld] esac
| Write (expr) -> [state, writeWorld(evalExpr(state, expr), world)]
| Skip -> c
| s -> failure ("Stmt eval not implemented\n")
esac
}

-- Evaluates a program with a given input and returns an output
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