path: root/awk/forth/f.awk

#!/usr/bin/awk -f

# Forth interpreter in AWK

BEGIN {
    print "Welcome to the AWK Forth Interpreter!"
    print "Type your commands below. Use 'bye' to quit."
    # Initialize variables
    top = -1  # Initialize stack pointer
    
    # Initialize the dictionary with basic words
    words["+"] = "+"
    words["-"] = "-"
    words["*"] = "*"
    words["/"] = "/"
    words["dup"] = "dup"
    words["over"] = "over"
    words["swap"] = "swap"
    words["."] = "."
    words["bye"] = "bye"
    words["rot"] = "rot"
    words["drop"] = "drop"
    words["nip"] = "nip"
    words["tuck"] = "tuck"
    words["roll"] = "roll"
    words["pick"] = "pick"
    words["negate"] = "negate"
    words["abs"] = "abs"
    words["max"] = "max"
    words["min"] = "min"
    words["mod"] = "mod"
    words["="] = "="
    words["see"] = "see"

    # Add descriptions for words
    desc["+"] = "( n1 n2 -- sum ) Add top two numbers"
    desc["-"] = "( n1 n2 -- diff ) Subtract top number from second"
    desc["*"] = "( n1 n2 -- prod ) Multiply top two numbers"
    desc["/"] = "( n1 n2 -- quot ) Divide second by top"
    desc["dup"] = "( n -- n n ) Duplicate top of stack"
    desc["over"] = "( n1 n2 -- n1 n2 n1 ) Copy second item to top"
    desc["swap"] = "( n1 n2 -- n2 n1 ) Swap top two items"
    desc["rot"] = "( n1 n2 n3 -- n2 n3 n1 ) Rotate top three items"
    desc["drop"] = "( n -- ) Discard top item"
    desc["nip"] = "( n1 n2 -- n2 ) Remove second item"
    desc["tuck"] = "( n1 n2 -- n2 n1 n2 ) Copy top item below second"
    desc["roll"] = "( nk ... n1 n0 k -- nk-1 ... n1 n0 nk ) Move kth item to top"
    desc["pick"] = "( nk ... n1 n0 k -- nk ... n1 n0 nk ) Copy kth item to top"
    desc["negate"] = "( n -- -n ) Negate number"
    desc["abs"] = "( n -- |n| ) Absolute value"
    desc["max"] = "( n1 n2 -- max ) Maximum of top two numbers"
    desc["min"] = "( n1 n2 -- min ) Minimum of top two numbers"
    desc["mod"] = "( n1 n2 -- rem ) Remainder of n1/n2"
    desc["="] = "( n1 n2 -- flag ) Test if equal, leaves 1 if true, 0 if false"

    # Add variable-related words to dictionary
    words["variable"] = "variable"
    words["!"] = "!"
    words["@"] = "@"
    words["?"] = "?"

    # Add descriptions for the new words
    desc["variable"] = "( -- addr ) Create a variable"
    desc["!"] = "( n addr -- ) Store n at addr"
    desc["@"] = "( addr -- n ) Fetch contents of addr"
    desc["?"] = "( addr -- ) Print contents of addr"

    # Initialize test-related words
    words["test"] = "test"
    words["testing"] = "testing"
    desc["test"] = "( n1 n2 -- ) Compare values and report test result"
    desc["testing"] = "( -- ) Print test description"

    # Handle file input
    if (ARGC > 1) {
        print "Loading file:", ARGV[1]
        while ((getline < ARGV[1]) > 0) {
            if ($0 ~ /^[[:space:]]*$/) continue  # Skip empty lines
            print "> " $0
            process_line()
        }
        close(ARGV[1])
        exit
    }
}

# Function to define a new word
function define_word(name, definition) {
    words[name] = definition
}

# Stack to hold values
function push(value) {
    stack[++top] = value
}

function pop() {
    if (top < 0) {
        print "Error: Stack underflow"
        return 0
    }
    return stack[top--]
}

function add() {
    if (top < 1) {
        print "Error: Not enough values on the stack"
        return
    }
    push(pop() + pop())
}

# Function for subtraction
function subtract() {
    if (top < 1) {
        print "Error: Not enough values on the stack"
        return
    }
    second = pop()
    first = pop()
    push(first - second)
}

# Function for multiplication
function multiply() {
    if (top < 1) {
        print "Error: Not enough values on the stack"
        return
    }
    push(pop() * pop())
}

# Function for division
function divide() {
    if (top < 1) {
        print "Error: Not enough values on the stack"
        return
    }
    second = pop()
    if (second == 0) {
        print "Error: Division by zero"
        return
    }
    first = pop()
    push(first / second)
}

# Function to duplicate the top value
function dup() {
    if (top < 0) {
        print "Error: Stack is empty"
        return
    }
    push(stack[top])  # Push the top value again
}

# Function to copy the second value to the top
function over() {
    if (top < 1) {
        print "Error: Not enough values on the stack"
        return
    }
    push(stack[top - 1])  # Push the second value
}

# Function to swap the top two values
function swap() {
    if (top < 1) {
        print "Error: Not enough values on the stack"
        return
    }
    temp = pop()  # Pop the top value
    second = pop()  # Pop the second value
    push(temp)  # Push the first value back
    push(second)  # Push the second value back
}

function print_top() {
    if (top < 0) {
        print "Error: Stack is empty"
        return
    }
    print stack[top]
}

# Function to list all available words
function list_words() {
    print "Available words:"
    for (word in words) {
        print word
    }
}

# Add these new functions after the existing stack manipulation functions:

function rot() {
    if (top < 2) {
        print "Error: Not enough values on stack"
        return
    }
    third = pop()
    second = pop()
    first = pop()
    push(second)
    push(third)
    push(first)
}

function drop() {
    if (top < 0) {
        print "Error: Stack underflow"
        return
    }
    top--
}

function nip() {
    if (top < 1) {
        print "Error: Not enough values on stack"
        return
    }
    temp = stack[top]    # Save top value
    drop()              # Remove top value
    drop()              # Remove second value
    push(temp)          # Put original top value back
}

function tuck() {
    if (top < 1) {
        print "Error: Not enough values on stack"
        return
    }
    temp = pop()
    second = pop()
    push(temp)
    push(second)
    push(temp)
}

function roll() {
    if (top < 0) {
        print "Error: Stack underflow"
        return
    }
    n = int(pop())
    if (top < n) {
        print "Error: Stack underflow"
        return
    }
    if (n <= 0) return

    # Store the item to be moved
    temp = stack[top - n + 1]
    
    # Shift the other items down
    for (i = top - n + 1; i < top; i++) {
        stack[i] = stack[i + 1]
    }
    
    # Put the rolled item on top
    stack[top] = temp
}

function pick() {
    if (top < 0) {
        print "Error: Stack underflow"
        return
    }
    n = int(pop())
    if (top < n) {
        print "Error: Stack underflow"
        return
    }
    if (n < 0) return
    
    push(stack[top - n])
}

function negate() {
    if (top < 0) {
        print "Error: Stack underflow"
        return
    }
    push(-pop())
}

function abs() {
    if (top < 0) {
        print "Error: Stack underflow"
        return
    }
    n = pop()
    push(n < 0 ? -n : n)
}

function max() {
    if (top < 1) {
        print "Error: Not enough values on stack"
        return
    }
    b = pop()
    a = pop()
    push(a > b ? a : b)
}

function min() {
    if (top < 1) {
        print "Error: Not enough values on stack"
        return
    }
    b = pop()
    a = pop()
    push(a < b ? a : b)
}

function mod() {
    if (top < 1) {
        print "Error: Not enough values on stack"
        return
    }
    b = pop()
    if (b == 0) {
        print "Error: Division by zero"
        push(b)
        return
    }
    a = pop()
    push(a % b)
}

function equals() {
    if (top < 1) {
        print "Error: Not enough values on stack"
        return
    }
    push((pop() == pop()) ? 1 : 0)
}

function see(word) {
    if (word in desc) {
        print desc[word]
    } else if (word in words) {
        print ": " word " " words[word] " ;"
    } else {
        print "Word '" word "' not found"
    }
}

# Add these new functions for variable handling:

# Function to create a new variable
function create_variable(name) {
    if (name == "") {
        print "Error: Variable name required"
        return
    }
    variables[name] = 0  # Initialize variable to 0
    push(name)          # Push variable name (address) onto stack
}

# Function to store a value in a variable
function store() {
    if (top < 1) {
        print "Error: Not enough values on stack"
        return
    }
    addr = pop()
    if (!(addr in variables)) {
        print "Error: Invalid variable '" addr "'"
        return
    }
    variables[addr] = pop()
}

# Function to fetch a value from a variable
function fetch() {
    if (top < 0) {
        print "Error: Stack underflow"
        return
    }
    addr = pop()
    if (!(addr in variables)) {
        print "Error: Invalid variable '" addr "'"
        return
    }
    push(variables[addr])
}

# Function to print a variable's value
function print_var() {
    if (top < 0) {
        print "Error: Stack underflow"
        return
    }
    addr = pop()
    if (!(addr in variables)) {
        print "Error: Invalid variable '" addr "'"
        return
    }
    print variables[addr]
}

# Add these test-related functions:
function run_test(expected) {
    if (top < 0) {
        print "❌ FAIL: Stack is empty"
        return
    }
    actual = pop()
    if (actual == expected) {
        print "✓ PASS"
    } else {
        print "❌ FAIL: Expected", expected, "but got", actual
    }
}

function print_test_description() {
    if (NF < 2) {
        print "Error: testing requires a description"
        return
    }
    # Collect all words after 'testing' as the description
    test_desc = ""
    for (i = 2; i <= NF; i++) {
        test_desc = test_desc " " $i
    }
    print "\nTesting:" test_desc
}

# Move the main command processing into a function
function process_line() {
    # Process input only if it's not empty
    if (NF > 0) {
        # Remove comments
        gsub(/\(.*\)/, "")  # Remove everything from ( to )

        # Check for word definitions
        if ($1 == ":") {
            word_name = $2
            definition = ""
            for (i = 3; i <= NF; i++) {
                if ($i == ";") {
                    define_word(word_name, definition)
                    print "Defined new word: " word_name
                    break
                } else {
                    definition = definition " " $i
                }
            }
            return
        }

        # Process remaining input
        for (i = 1; i <= NF; i++) {
            if ($i ~ /^-?[0-9]+$/) {  # Modified to handle negative numbers
                push($i)  # Push numbers onto the stack
            } else if ($i in variables) {  # Check for variables BEFORE words
                push($i)  # Push variable name onto stack
            } else if ($i in words) {
                # If the word is defined, execute its definition
                if (words[$i] == "+") add()
                else if (words[$i] == "-") subtract()
                else if (words[$i] == "*") multiply()
                else if (words[$i] == "/") divide()
                else if (words[$i] == "dup") dup()
                else if (words[$i] == "over") over()
                else if (words[$i] == "swap") swap()
                else if (words[$i] == ".") print_top()
                else if (words[$i] == "bye") exit
                else if (words[$i] == "words") list_words()
                else if (words[$i] == "rot") rot()
                else if (words[$i] == "drop") drop()
                else if (words[$i] == "nip") nip()
                else if (words[$i] == "tuck") tuck()
                else if (words[$i] == "roll") roll()
                else if (words[$i] == "pick") pick()
                else if (words[$i] == "negate") negate()
                else if (words[$i] == "abs") abs()
                else if (words[$i] == "max") max()
                else if (words[$i] == "min") min()
                else if (words[$i] == "mod") mod()
                else if (words[$i] == "=") equals()
                else if (words[$i] == "see") {
                    if (i + 1 <= NF) {
                        see($(i + 1))
                        i++  # Skip the word name
                    } else {
                        print "Error: see requires a word name"
                    }
                }
                else if (words[$i] == "variable") {
                    if (i + 1 <= NF) {
                        create_variable($(i + 1))
                        i++  # Skip the variable name
                    } else {
                        print "Error: variable requires a name"
                    }
                }
                else if (words[$i] == "!") store()
                else if (words[$i] == "@") fetch()
                else if (words[$i] == "?") print_var()
                else if (words[$i] == "test") {
                    if (i + 1 <= NF) {
                        run_test($(i + 1))
                        i++  # Skip the expected value
                    } else {
                        print "Error: test requires an expected value"
                    }
                }
                else if (words[$i] == "testing") {
                    print_test_description()
                    return
                }
                else {
                    # Execute user-defined word
                    split(words[$i], cmd, " ")
                    for (j = 1; j <= length(cmd); j++) {
                        command = cmd[j]
                        if (command ~ /^-?[0-9]+$/) {  # Modified for negative numbers
                            push(command)
                        } else if (command in variables) {  # Check for variables
                            push(command)
                        } else if (command in words) {
                            # Recursive execution of defined words
                            if (words[command] == "+") add()
                            else if (words[command] == "-") subtract()
                            else if (words[command] == "*") multiply()
                            else if (words[command] == "/") divide()
                            else if (words[command] == "dup") dup()
                            else if (words[command] == "over") over()
                            else if (words[command] == "swap") swap()
                            else if (words[command] == ".") print_top()
                            else if (words[command] == "bye") exit
                            else if (words[command] == "words") list_words()
                            else if (words[command] == "!") store()
                            else if (words[command] == "@") fetch()
                            else if (words[command] == "?") print_var()
                            else if (words[command] == "see") {
                                if (i + 1 <= NF) {
                                    see($(i + 1))
                                    i++  # Skip the word name
                                } else {
                                    print "Error: see requires a word name"
                                }
                            }
                        }
                    }
                }
            } else if ($i == "+") {
                add()
            } else if ($i == "-") {
                subtract()
            } else if ($i == "*") {
                multiply()
            } else if ($i == "/") {
                divide()
            } else if ($i == "dup") {
                dup()
            } else if ($i == "over") {
                over()
            } else if ($i == "swap") {
                swap()
            } else if ($i == ".") {
                print_top()
            } else if ($i == "bye") {
                exit
            } else if ($i == "words") {
                list_words()
            } else if ($i != "") {  # Ignore empty tokens
                print "Error: Unknown command '" $i "'"
            }
        }
    }
}

# Main loop to read commands (for interactive mode)
{
    process_line()
}