Support all the types of EOF

README.md

@@ -20,9 +20,6 @@ Gir supports following optimizations:
 
 TODO
 ----
-### gir.js
-* Support for other types of EOF?
-
 ### gir.html
 * Implement a UI
 

brainfuck.md

@@ -11,10 +11,13 @@ cells that wrap around
 
 IO
 --
-`.` and `,` operate on a utf-8 stream. `,` produces `0` on EOF
+`.` and `,` operate on a utf-8 stream. `,` produces `0` by default on EOF.
+This can be changed by passing a third parameter to newVM, where 0/-1 sets
+the cell to that and null keeps it unchanged
 
 `:` produces a decimal representation of the current cell. `;` skips any
 space (U+20) characters in the input stream and then reads 1 or more ASCII
 digit (U+30 to U+39), clamps the number to the range [0, 255] and sets the
-cell to it. If it can't read a digit and EOF has been reached it returns 0,
-but if EOF hasn't been reached it raises an error flag and stops execution
+cell to it. If it can't read a digit and EOF has been reached it produces an
+EOF similarily to `,` (by default sets to 0, but can be changed), but if EOF
+hasn't been reached it raises an error flag and stops execution

gir.js

@@ -573,8 +573,10 @@ function optimize(parsed) {
 // Virtual machine
 // ------------------------------------------------------------------
 
-// ([flatCommandObject], [int]) → girVMState
-function newVM(program, input) {
+// ([flatCommandObject], [int], int/null) → girVMState
+// onEof tells what to set the cell to in case of EOF, or if it null to keep
+// the same value
+function newVM(program, input, onEof = 0) {
 	return {
 		// Initial state for the machine
 		program: program,
@@ -584,7 +586,10 @@ function newVM(program, input) {
 		tapeHead: 0,
 
 		input: input,
-		output: []
+		output: [],
+
+		// Configuration
+		onEof: onEof
 	};
 }
 
@@ -684,8 +689,15 @@ function runVM(state, maxCycles = null) {
 			case readByte:
 				// Have we reached EOF?
 				if(input.length == 0) {
-					// Yes, return 0
-					memory.set(index, 0);
+					// Yes
+					// If state.onEof is null, don't
+					// change the value
+					// If it's something else, set the
+					// cell to that
+					if(state.onEof !== null) {
+						memory.set(index,
+							state.onEof & 0xff);
+					}
 				} else {
 					// No, return character
 					memory.set(index, input.shift());
@@ -765,9 +777,15 @@ function runVM(state, maxCycles = null) {
 						0);
 					memory.set(index, number);
 				} else if(input.length == 0) {
-					// No, but there was an EOF, so set
-					// the cell to 0
-					memory.set(index, 0);
+					// No, but there was an EOF
+					// If state.onEof is null, don't
+					// change the value
+					// If it's something else, set the
+					// cell to that
+					if(state.onEof !== null) {
+						memory.set(index,
+							state.onEof & 0xff);
+					}
 				} else {
 					// No, and there wasn't an EOF, so
 					// signal an error