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diff --git a/awk/scheme/scheme/docs/scheme-compiler-impl.md b/awk/scheme/scheme/docs/scheme-compiler-impl.md deleted file mode 100644 index db8a204..0000000 --- a/awk/scheme/scheme/docs/scheme-compiler-impl.md +++ /dev/null @@ -1,307 +0,0 @@ -# Scheme Compiler Implementation in AWK - -## Basic Compiler Structure - -We'll implement the compiler as a recursive descent processor that converts Scheme expressions into VM instructions. Here's the core structure: - -```awk -# Global state -BEGIN { - next_label = 0 # For generating unique labels - next_address = 0 # Current instruction address - depth = 0 # Current environment depth -} - -# Main compile function -function compile(expr, parts, len) { - if (isAtom(expr)) - return compileAtom(expr) - - split(expr, parts, " ") - len = length(parts) - - # Strip parentheses - parts[1] = substr(parts[1], 2) # Remove leading ( - parts[len] = substr(parts[len], 1, length(parts[len])-1) # Remove trailing ) - - # Dispatch based on first element - if (parts[1] == "+") - return compileAdd(parts, len) - else if (parts[1] == "let") - return compileLet(parts, len) - else if (parts[1] == "lambda") - return compileLambda(parts, len) - else if (parts[1] == "if") - return compileIf(parts, len) - else - return compileCall(parts, len) -} - -# Utility functions -function isAtom(expr) { - return substr(expr, 1, 1) != "(" -} - -function newLabel() { - return "L" next_label++ -} - -function emit(instr) { - program[next_address++] = instr -} -``` - -## Compilation Patterns - -### 1. Basic Arithmetic - -```awk -function compileAdd(parts, len, i) { - # Compile each argument - for (i = 2; i <= len; i++) - compile(parts[i]) - - # Emit adds between each value - for (i = 3; i <= len; i++) - emit("ADD") - - return next_address - 1 -} - -# Example usage: -# Input: (+ 1 2 3) -# Output: -# PUSH_CONST N:1 -# PUSH_CONST N:2 -# ADD -# PUSH_CONST N:3 -# ADD -``` - -### 2. Let Expressions - -```awk -function compileLet(parts, len, bindings, body, i, num_bindings) { - # Parse let structure - bindings = parts[2] - body = parts[3] - - # Count bindings - split(bindings, binding_parts, " ") - num_bindings = (length(binding_parts) - 2) / 2 # Account for parentheses - - # Create new environment frame - emit("MAKE_ENV " num_bindings) - - # Compile each binding value and store - for (i = 1; i <= num_bindings; i++) { - compile(binding_parts[i * 2]) - emit("STORE_LOCAL " (i - 1)) - } - - # Compile body in new environment - depth++ - compile(body) - depth-- - - return next_address - 1 -} - -# Example usage: -# Input: (let ((x 5)) (+ x 1)) -# Output: -# MAKE_ENV 1 -# PUSH_CONST N:5 -# STORE_LOCAL 0 -# LOAD_LOCAL 0 -# PUSH_CONST N:1 -# ADD -``` - -### 3. Lambda Expressions - -```awk -function compileLambda(parts, len, param_list, body, label_start, label_end) { - label_start = newLabel() - label_end = newLabel() - - # Emit jump around function body - emit("JUMP " label_end) - - # Mark function start - emit(label_start ":") - - # Parse parameters - param_list = parts[2] - body = parts[3] - - # Compile function body - depth++ - compile(body) - emit("RETURN") - depth-- - - # Mark function end - emit(label_end ":") - - # Create function object - emit("MAKE_FUNCTION " label_start) - - return next_address - 1 -} - -# Example usage: -# Input: (lambda (x) (+ x 1)) -# Output: -# JUMP L1 -# L0: -# LOAD_LOCAL 0 -# PUSH_CONST N:1 -# ADD -# RETURN -# L1: -# MAKE_FUNCTION L0 -``` - -### 4. If Expressions - -```awk -function compileIf(parts, len, condition, true_branch, false_branch, label_else, label_end) { - label_else = newLabel() - label_end = newLabel() - - # Compile condition - compile(parts[2]) - - # Jump to else if false - emit("JUMP_IF_FALSE " label_else) - - # Compile true branch - compile(parts[3]) - emit("JUMP " label_end) - - # Compile false branch - emit(label_else ":") - if (len > 4) # If there is an else branch - compile(parts[4]) - - emit(label_end ":") - - return next_address - 1 -} - -# Example usage: -# Input: (if (< x 0) (- 0 x) x) -# Output: -# LOAD_LOCAL 0 -# PUSH_CONST N:0 -# NUM_LT -# JUMP_IF_FALSE L0 -# PUSH_CONST N:0 -# LOAD_LOCAL 0 -# SUB -# JUMP L1 -# L0: -# LOAD_LOCAL 0 -# L1: -``` - -### 5. Function Calls - -```awk -function compileCall(parts, len, i, num_args) { - num_args = len - 1 - - # Compile each argument - for (i = 2; i <= len; i++) - compile(parts[i]) - - # Compile function reference - compile(parts[1]) - - # Emit call instruction - emit("CALL " num_args) - - return next_address - 1 -} - -# Example usage: -# Input: (add1 5) -# Output: -# PUSH_CONST N:5 -# LOAD_GLOBAL 0 -# CALL 1 -``` - -## Symbol Table Management - -```awk -# Track variables and their locations -function enterScope() { - scope_depth++ - next_local = 0 -} - -function leaveScope() { - scope_depth-- -} - -function addLocal(name) { - symbols[scope_depth "," name] = next_local++ -} - -function findVariable(name, i) { - for (i = scope_depth; i >= 0; i--) - if ((i "," name) in symbols) - return "LOCAL " i "," symbols[i "," name] - return "GLOBAL " name -} -``` - -## Example Usage - -Here's how to use the compiler: - -```awk -BEGIN { - # Initialize compiler - next_label = 0 - next_address = 0 - depth = 0 - - # Compile some example code - expr = "(let ((x 5)) (+ x 1))" - compile(expr) - - # Print generated code - for (i = 0; i < next_address; i++) - print i ": " program[i] -} -``` - -## Implementation Notes - -1. Variable Resolution - - Track scope depth for proper variable lookup - - Generate appropriate LOAD/STORE instructions - - Handle closure captures - -2. Label Generation - - Use unique labels for control flow - - Track label addresses for jumps - -3. Environment Management - - Track environment depth - - Generate correct frame sizes - - Handle nested scopes - -4. Error Handling - - Check for syntax errors - - Validate number of arguments - - Report meaningful errors - -5. Optimization Opportunities - - Tail call detection - - Constant folding - - Peephole optimization - - Dead code elimination |