1 files changed, 139 insertions, 0 deletions
diff --git a/awk/scheme/s.awk b/awk/scheme/s.awk
new file mode 100755
index 0000000..7c8bba6
--- /dev/null
+++ b/awk/scheme/s.awk
@@ -0,0 +1,139 @@
+#!/usr/bin/awk -f
+
+# Set debug mode
+DEBUG = 1  # Change to 0 to disable debug output
+
+# Environment to store variable bindings
+BEGIN {
+    print "Welcome to the AWK Scheme Interpreter!"
+    print "Type your Scheme expressions below (type 'exit' to quit):"
+    while (1) {
+        printf "> "
+        if (getline input <= 0) {
+            print "Error reading input. Exiting."
+            break
+        }
+        if (input == "exit") {
+            print "Exiting the interpreter."
+            exit
+        }
+        if (input == "") {
+            print "Empty input received, continuing..."
+            continue
+        }
+        
+        print "Input received: " input  # Echo the input
+        ast = parse(input)  # Parse the input
+        
+        # Print the entire AST for debugging
+        for (i = 1; i <= length(ast); i++) {
+            print "AST[" i "] = " ast[i]
+        }
+        
+        # Evaluate the AST
+        if (length(ast) > 0) {
+            result = eval(ast)  # Evaluate the AST
+            print "Result: " result  # Print the result
+        } else {
+            print "Parsed AST is empty."
+        }
+    }
+}
+
+# Function to parse input into an AST
+function parse(input) {
+    # Remove outer whitespace
+    gsub(/^\s+|\s+$/, "", input)
+    
+    # Check if input is empty after trimming
+    if (input == "") {
+        print "Input is empty after trimming"
+        return ""
+    }
+    
+    # Debugging: Print input before processing
+    print "Debug: Raw input for parsing: " input
+    
+    # Remove parentheses at start and end
+    if (substr(input, 1, 1) == "(") {
+        input = substr(input, 2)
+    }
+    if (substr(input, length(input), 1) == ")") {
+        input = substr(input, 1, length(input) - 1)
+    }
+    
+    # Debugging: Print input after removing outer parentheses
+    print "Debug: Input after removing outer parentheses: " input
+    
+    # Split the input into tokens
+    gsub(/\(/, " ( ", input)
+    gsub(/\)/, " ) ", input)
+    gsub(/\s+/, " ", input)  # normalize whitespace
+    gsub(/^\s+|\s+$/, "", input)  # trim
+    
+    # Debugging: Print input after tokenization
+    print "Debug: Input after tokenization: " input
+    
+    n = split(input, ast, " ")
+    
+    # Debugging: Print the number of tokens
+    print "Debug: Number of tokens: " n
+    
+    return ast
+}
+
+# Function to evaluate the AST
+function eval(ast,    i, result) {
+    # Debugging: Print the current AST being evaluated
+    print "Debug: Evaluating AST: " ast[1] " " ast[2] " " ast[3]
+    
+    # Handle numbers directly
+    if (ast[1] ~ /^[+-]?[0-9]+$/) {
+        print "Debug: Returning number: " ast[1]
+        return ast[1] + 0  # Convert string to number
+    }
+    
+    # Handle addition
+    if (ast[1] == "+") {
+        result = 0
+        for (i = 2; i <= length(ast); i++) {
+            print "Debug: Adding operand: " ast[i]
+            result += eval(ast[i])  # Recursively evaluate operands
+        }
+        return result
+    }
+    
+    # Handle subtraction
+    if (ast[1] == "-") {
+        result = eval(ast[2])  # Start with the first operand
+        for (i = 3; i <= length(ast); i++) {
+            print "Debug: Subtracting operand: " ast[i]
+            result -= eval(ast[i])  # Subtract subsequent operands
+        }
+        return result
+    }
+    
+    # Handle multiplication
+    if (ast[1] == "*") {
+        result = 1
+        for (i = 2; i <= length(ast); i++) {
+            print "Debug: Multiplying operand: " ast[i]
+            result *= eval(ast[i])  # Multiply operands
+        }
+        return result
+    }
+    
+    # Handle division
+    if (ast[1] == "/") {
+        result = eval(ast[2])  # Start with the first operand
+        for (i = 3; i <= length(ast); i++) {
+            print "Debug: Dividing by operand: " ast[i]
+            result /= eval(ast[i])  # Divide by subsequent operands
+        }
+        return result
+    }
+    
+    # If we reach here, the operation is not recognized
+    return "Error: Unknown operation " ast[1]
+}
+