Added buffer in get_ch() for line continuation lookahead

pnut.c

@@ -49,6 +49,8 @@
 // Use positional parameter directly for function parameters that are constants
 #define OPTIMIZE_CONSTANT_PARAM_not
 #define SUPPORT_ADDRESS_OF_OP_not
+// Make get_ch() use a length-1 character buffer to lookahead and skip line continuations
+#define SUPPORT_LINE_CONTINUATION
 
 // Shell backend codegen options
 #ifndef SH_AVOID_PRINTF_USE_NOT
@@ -247,7 +249,11 @@ void syntax_error(char *msg) {
 
 // tokenizer
 
+#define CHBUF_SIZE 1
 int ch;
+int chbuf[CHBUF_SIZE];
+int chbuf_head = -1;
+int chbuf_tail = 0;
 #ifdef DEBUG_EXPAND_INCLUDES
 int prev_ch = EOF;
 #endif
@@ -757,7 +763,35 @@ void output_declaration_c_code(bool no_header) {
 #endif
 
 void get_ch() {
+#ifdef SUPPORT_LINE_CONTINUATION
+  if(chbuf_head > -1) {
+    ch = chbuf[chbuf_head++];
+    if(chbuf_head == chbuf_tail) {
+      chbuf_head = -1;
+    }
+  } else {
+    ch = fgetc(fp);
+
+    if(ch == '\\') {
+      ch = fgetc(fp);
+
+      if(ch != '\n'){   // The character isn't a newline, so this is an escape sequence:
+        chbuf[0] = ch;  // Put the character back in the character buffer for future consumption
+        chbuf_tail = 1; // Set the character buffer size
+        chbuf_head = 0; // Set the pointer to the character buffer
+        ch = '\\';      // Restore the character that was read on this call
+      } else {          // The character is a newline, so this is a line continuation which we want to bypass
+        ch = fgetc(fp); // Consume yet another character, the next one for logical parsing
+#ifdef INCLUDE_LINE_NUMBER_ON_ERROR
+        line_number += 1;
+        column_number = 0;
+#endif
+      }
+    }
+  }
+#else
   ch = fgetc(fp);
+#endif
   if (ch == EOF) {
     // If it's not the last file on the stack, EOF means that we need to switch to the next file
     if (include_stack->next != 0) {

tests/_all/line_continuation.c

@@ -0,0 +1,36 @@
+#include <stdio.h>
+
+void putint_aux(int n, int base) {
+  int d = n % base;
+  int top = n / base;
+  if (n == 0) return;
+  putint_aux(top, base);
+  putchar("0123456789abcdef"[d & 15]);
+}
+
+void putint(int n, int base) {
+  if (n < 0) {
+    putchar('-');
+    putint_aux(-n, base);
+  } else {
+    putint_aux(n, base);
+  }
+}
+
+void main() {
+
+/**/
+int foo = 0;
+
+/\
+*
+*/ fo\
+o +\
+= 0\
+x\
+10\
+200;
+
+    putint(foo, 10);
+    return 0;
+}

tests/_all/line_continuation.golden

@@ -0,0 +1 @@
+66048