June 2018 Update

Task/Execute-Brain----/Julia/execute-brain----.julia

@@ -0,0 +1,38 @@
+using DataStructures
+
+function execute(src)
+    pointers = Dict{Int,Int}()
+    stack    = Int[]
+    for (ptr, opcode) in enumerate(src)
+        if opcode == '[' push!(stack, ptr) end
+        if opcode == ']'
+            if isempty(stack)
+                src = src[1:ptr]
+                break
+            end
+            sptr = pop!(stack)
+            pointers[ptr], pointers[sptr] = sptr, ptr
+        end
+    end
+    if ! isempty(stack) error("unclosed loops at $stack") end
+    tape = DefaultDict{Int,Int}(0)
+    cell, ptr = 0, 1
+    while ptr ≤ length(src)
+        opcode = src[ptr]
+        if     opcode == '>' cell += 1
+        elseif opcode == '<' cell -= 1
+        elseif opcode == '+' tape[cell] += 1
+        elseif opcode == '-' tape[cell] -= 1
+        elseif opcode == ',' tape[cell] = Int(read(STDIN, 1))
+        elseif opcode == '.' print(STDOUT, Char(tape[cell]))
+        elseif (opcode == '[' && tape[cell] == 0) ||
+               (opcode == ']' && tape[cell] != 0) ptr = pointers[ptr]
+        end
+        ptr += 1
+    end
+end
+
+const src = """\
+    >++++++++[<+++++++++>-]<.>>+>+>++>[-]+<[>[->+<<++++>]<<]>.+++++++..+++.>
+    >+++++++.<<<[[-]<[-]>]<+++++++++++++++.>>.+++.------.--------.>>+.>++++."""
+execute(src)