// Part 1 about an Interpreter for the Brainf***++ language//========================================================object CW10a { import io.Sourceimport scala.util._type Mem = Map[Int, Int]// (1) Write a function that takes a file name as argument and// and requests the corresponding file from disk. It returns the// content of the file as a String. If the file does not exists,// the function should return the empty string.def load_bff(name: String) : String = Try(Source.fromFile(name)("ISO-8859-1").mkString).getOrElse("")// (2) Complete the functions for safely reading // and writing brainf***++ memory. Safely read should// Return the value stored in the Map for a given memory// pointer, provided it exists; otherwise it Returns 0. The// writing function generates a new Map with the// same data, except at the given memory pointer the// value v is stored.def sread(mem: Mem, mp: Int) : Int = mem.getOrElse(mp, 0)def write(mem: Mem, mp: Int, v: Int) : Mem = mem.updated(mp, v)// (3) Implement the two jumping instructions in the // brainf***++ language. In jumpRight, given a program and // a program counter move the program counter to the right // until after the *matching* ]-command. Similarly, // jumpLeft implements the move to the left to just after// the *matching* [-command.def jumpRight(prog: String, pc: Int, level: Int) : Int = { if (prog.length <= pc) pc else (prog(pc), level) match { case (']', 0) => pc + 1 case (']', l) => jumpRight(prog, pc + 1, l - 1) case ('[', l) => jumpRight(prog, pc + 1, l + 1) case (_, l) => jumpRight(prog, pc + 1, l) }}def jumpLeft(prog: String, pc: Int, level: Int) : Int = { if (pc < 0) pc else (prog(pc), level) match { case ('[', 0) => pc + 1 case ('[', l) => jumpLeft(prog, pc - 1, l - 1) case (']', l) => jumpLeft(prog, pc - 1, l + 1) case (_, l) => jumpLeft(prog, pc - 1, l) }}// test cases//jumpRight("""--[..+>--].>.++""", 3, 0) // => 10//jumpLeft("""--[..+>--].>.++""", 8, 0) // => 3//jumpRight("""--[..[+>]--].>.++""", 3, 0) // => 12//jumpRight("""--[..[[-]+>[.]]--].>.++""", 3, 0) // => 18//jumpRight("""--[..[[-]+>[.]]--.>.++""", 3, 0) // => 22 (outside)//jumpLeft("""[******]***""", 7, 0) // => -1 (outside)// (4) Complete the compute function that interprets (runs) a brainf***++// program: the arguments are a program (represented as a string), a program // counter, a memory counter and a brainf***++ memory. It Returns the// memory at the stage when the execution of the brainf***++ program// finishes. The interpretation finishes once the program counter// pc is pointing to something outside the program string.// If the pc points to a character inside the program, the pc, // memory pointer and memory need to be updated according to // rules of the brainf***++ language. Then, recursively, the compute // function continues with the command at the new program// counter. // Implement the run function that calls compute with the program// counter and memory counter set to 0.def compute(prog: String, pc: Int, mp: Int, mem: Mem) : Mem = { if (0 <= pc && pc < prog.length) { val (new_pc, new_mp, new_mem) = prog(pc) match { case '>' => (pc + 1, mp + 1, mem) case '<' => (pc + 1, mp - 1, mem) case '+' => (pc + 1, mp, write(mem, mp, sread(mem, mp) + 1)) case '-' => (pc + 1, mp, write(mem, mp, sread(mem, mp) - 1)) case '.' => { print(sread(mem, mp).toChar); (pc + 1, mp, mem) } //case ',' => (pc + 1, mp, write(mem, mp, Console.in.read().toByte)) //case ',' => (pc + 1, mp, write(mem, mp, scala.io.StdIn.readByte())) case '[' => if (sread(mem, mp) == 0) (jumpRight(prog, pc + 1, 0), mp, mem) else (pc + 1, mp, mem) case ']' => if (sread(mem, mp) != 0) (jumpLeft(prog, pc - 1, 0), mp, mem) else (pc + 1, mp, mem) // new commands case '@' => (pc + 1, mp, write(mem, sread(mem, mp), sread(mem, mp - 1))) case '*' => (pc + 1, mp, write(mem, mp, sread(mem, mp) * sread(mem, mp -1))) case '#' => { println(s"${sread(mem, mp)}"); (pc + 1, mp, mem) } case _ => (pc + 1, mp, mem) } compute(prog, new_pc, new_mp, new_mem) } else mem}def run(prog: String, m: Mem = Map()) = compute(prog, 0, 0, m)// some sample bf/bf++-programs collected from the Internet//==========================================================// some contrived (small) programs//---------------------------------// clears the 0-cell//run("[-]", Map(0 -> 100)) // Map will be 0 -> 0// moves content of the 0-cell to 1-cell//run("[->+<]", Map(0 -> 10)) // Map will be 0 -> 0, 1 -> 10// copies content of the 0-cell to 2-cell and 4-cell//run("[>>+>>+<<<<-]", Map(0 -> 42)) // Map(0 -> 0, 2 -> 42, 4 -> 42)// prints out numbers 0 to 9//run("""+++++[->++++++++++<]>--<+++[->>++++++++++<<]>>++<<----------[+>.>.<+<]""")// bf++ program calculating the cube-function, 10 * 10 * 10 = 1000//run("""++++++++++#>+***#""") // Map(0 -> 10, 1 -> 1000)// bf++ program copies 3 from 0-cell to to cells 1, 4, 5, 6 and 7// (note that because of how the program wprks cell 1 will contain 7) //run("""+++>+@+@+@+@+@""") // Map(0 -> 3, 1 -> 7, 4 -> 3, 5 -> 3, 6 -> 3, 7 -> 3)// some more "useful" programs//-----------------------------// hello world program 1//run("""++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++// ..+++.>>.<-.<.+++.------.--------.>>+.>++.""")// hello world program 2//run("""++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>+// +.<<+++++++++++++++.>.+++.------.--------.>+.>.""")// hello world program 3//run("""+++++++++[>++++++++>+++++++++++>+++++<<<-]>.>++.+++++++..// +++.>-.------------.<++++++++.--------.+++.------.--------.>+.""")// draws the Sierpinski triangle//run(load_bff("sierpinski.bf"))//fibonacci numbers below 100//run("""+++++++++++// >+>>>>++++++++++++++++++++++++++++++++++++++++++++// >++++++++++++++++++++++++++++++++<<<<<<[>[>>>>>>+>// +<<<<<<<-]>>>>>>>[<<<<<<<+>>>>>>>-]<[>++++++++++[-// <-[>>+>+<<<-]>>>[<<<+>>>-]+<[>[-]<[-]]>[<<[>>>+<<<// -]>>[-]]<<]>>>[>>+>+<<<-]>>>[<<<+>>>-]+<[>[-]<[-]]// >[<<+>>[-]]<<<<<<<]>>>>>[+++++++++++++++++++++++++// +++++++++++++++++++++++.[-]]++++++++++<[->-<]>++++// ++++++++++++++++++++++++++++++++++++++++++++.[-]<<// <<<<<<<<<<[>>>+>+<<<<-]>>>>[<<<<+>>>>-]<-[>>.>.<<<// [-]]<<[>>+>+<<<-]>>>[<<<+>>>-]<<[<+>-]>[<+>-]<<<-]""")//outputs the square numbers up to 10000//run("""++++[>+++++<-]>[<+++++>-]+<+[>[>+>+<<-]++>>[<<+>>-]>>>[-]++>[-]+// >>>+[[-]++++++>>>]<<<[[<++++++++<++>>-]+<.<[>----<-]<]// <<[>>>>>[>>>[-]+++++++++<[>-<-]+++++++++>[-[<->-]+[<<<]]<[>+<-]>]<<-]<<-]""")// calculates 2 to the power of 6 //(example from a C-to-BF compiler at https://github.com/elikaski/BF-it)//run(""">>[-]>[-]++>[-]++++++><<<>>>>[-]+><>[-]<<[-]>[>+<<+>-]>[<+>-]// <><[-]>[-]<<<[>>+>+<<<-]>>>[<<<+>>>-][-]><<>>[-]>[-]<<<[>>[-]// <[>+>+<<-]>[<+>-]+>[[-]<-<->>]<<<-]>>[<<+>>-]<<[[-]>[-]<<[>+>// +<<-]>>[<<+>>-][-]>[-]<<<<<[>>>>+>+<<<<<-]>>>>>[<<<<<+>>>>>-]// <<>>[-]>[-]<<<[>>>+<<<-]>>>[<<[<+>>+<-]>[<+>-]>-]<<<>[-]<<[-]// >[>+<<+>-]>[<+>-]<><[-]>[-]<<<[>>+>+<<<-]>>>-[<<<+>>>-]<[-]>[-]// <<<[>>+>+<<<-]>>>[<<<+>>>-][-]><<>>[-]>[-]<<<[>>[-]<[>+>+<<-]>// [<+>-]+>[[-]<-<->>]<<<-]>>[<<+>>-]<<][-]>[-]<<[>+>+<<-]>>[<<+>// >-]<<<<<[-]>>>>[<<<<+>>>>-]<<<<><>[-]<<[-]>[>+<<+>-]>[<+>-]<>// <[-]>[-]>[-]<<<[>>+>+<<<-]>>>[<<<+>>>-]<<>>[-]>[-]>[-]>[-]>[-]>// [-]>[-]>[-]>[-]>[-]<<<<<<<<<<>>++++++++++<<[->+>-[>+>>]>[+[-<+// >]>+>>]<<<<<<]>>[-]>>>++++++++++<[->-[>+>>]>[+[-<+>]>+>>]<<<<<// ]>[-]>>[>++++++[-<++++++++>]<.<<+>+>[-]]<[<[->-<]++++++[->++++// ++++<]>.[-]]<<++++++[-<++++++++>]<.[-]<<[-<+>]<<><<<""")// a Mandelbrot set generator in brainf*** written by Erik Bosman// (http://esoteric.sange.fi/brainfuck/utils/mandelbrot/)////run(load_bff("mandelbrot.bf"))// a benchmark program (counts down from 'Z' to 'A')////run(load_bff("benchmark.bf"))// calculates the Collatz series for numbers from 1 to 30////run(load_bff("collatz.bf"))}