diff -r a9d84442fb65 -r ec7a12806c3f marking5/bf.scala --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/marking5/bf.scala Wed Jan 16 12:20:34 2019 +0000 @@ -0,0 +1,225 @@ +// Part 1 about an Interpreter for the Brainf*** language +//======================================================== + +//object CW10a { // only for generating the Jar file + + +type Mem = Map[Int, Int] + + +import io.Source +import scala.util._ + +// (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 '[' => + 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) + 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-programs collected from the Internet +//===================================================== + + +// first some contrived (small) programs + +// clears the 0-cell +run("[-]", Map(0 -> 100)) // Map will be 0 -> 0 + +// copies 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)) + + +// prints out numbers 0 to 9 +run("""+++++[->++++++++++<]>--<+++[->>++++++++++<<]>>++<<----------[+>.>.<+<]""") + + +// some more "useful" programs + +// hello world program 1 +run("""++++++++[>++++[>++>+++>+++>+<<<<-]>+>+>->>+[<]<-]>>.>---.+++++++ + ..+++.>>.<-.<.+++.------.--------.>>+.>++.""") + +// hello world program 2 +run("""++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>+ + +.<<+++++++++++++++.>.+++.------.--------.>+.>.""") + + +// draws the Sierpinski triangle +run("""++++++++[>+>++++<<-]>++>>+<[-[>>+<<-]+>>]>+[-<<<[ + ->[+[-]+>++>>>-<<]<[<]>>++++++[<<+++++>>-]+<<++.[-]<< + ]>.>+[>>]>+]""") + +run(load_bff("sierpinski.bf")) + + +//fibonacci numbers below 100 +run("""+++++++++++ + >+>>>>++++++++++++++++++++++++++++++++++++++++++++ + >++++++++++++++++++++++++++++++++<<<<<<[>[>>>>>>+> + +<<<<<<<-]>>>>>>>[<<<<<<<+>>>>>>>-]<[>++++++++++[- + <-[>>+>+<<<-]>>>[<<<+>>>-]+<[>[-]<[-]]>[<<[>>>+<<< + -]>>[-]]<<]>>>[>>+>+<<<-]>>>[<<<+>>>-]+<[>[-]<[-]] + >[<<+>>[-]]<<<<<<<]>>>>>[+++++++++++++++++++++++++ + +++++++++++++++++++++++.[-]]++++++++++<[->-<]>++++ + ++++++++++++++++++++++++++++++++++++++++++++.[-]<< + <<<<<<<<<<[>>>+>+<<<<-]>>>>[<<<<+>>>>-]<-[>>.>.<<< + [-]]<<[>>+>+<<<-]>>>[<<<+>>>-]<<[<+>-]>[<+>-]<<<-]""") + + +//outputs the square numbers up to 10000 +run("""++++[>+++++<-]>[<+++++>-]+<+[ + >[>+>+<<-]++>>[<<+>>-]>>>[-]++>[-]+ + >>>+[[-]++++++>>>]<<<[[<++++++++<++>>-]+<.<[>----<-]<] + <<[>>>>>[>>>[-]+++++++++<[>-<-]+++++++++>[-[<->-]+[<<<]]<[>+<-]>]<<-]<<-]""") + +//collatz numbers (needs a number to be typed in) +run(""">,[[----------[ + >>>[>>>>]+[[-]+<[->>>>++>>>>+[>>>>]++[->+<<<<<]]<<<] + ++++++[>------<-]>--[>>[->>>>]+>+[<<<<]>-],<]>]>>>++>+>>[ + <<[>>>>[-]+++++++++<[>-<-]+++++++++>[-[<->-]+[<<<<]]<[>+<-]>] + >[>[>>>>]+[[-]<[+[->>>>]>+<]>[<+>[<<<<]]+<<<<]>>>[->>>>]+>+[<<<<]] + >[[>+>>[<<<<+>>>>-]>]<<<<[-]>[-<<<<]]>>>>>>> + ]>>+[[-]++++++>>>>]<<<<[[<++++++++>-]<.[-]<[-]<[-]<]<,]""") + + +// infinite collatz (never stops) +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') +val b1 = """>++[<+++++++++++++>-]<[[>+>+<<-]>[<+>-]++++++++ + [>++++++++<-]>.[-]<<>++++++++++[>++++++++++[>++ + ++++++++[>++++++++++[>++++++++++[>++++++++++[>+ + +++++++++[-]<-]<-]<-]<-]<-]<-]<-]++++++++++.""" + + +def time_needed[T](n: Int, code: => T) = { + val start = System.nanoTime() + for (i <- 0 until n) code + val end = System.nanoTime() + (end - start)/(n * 1.0e9) +} + +time_needed(1, run(b1)) +*/ + +//}