Further refine documentation

third_party/chibicc/file.c

@@ -0,0 +1,106 @@
+#include "third_party/chibicc/chibicc.h"
+
+// Slurps contents of file.
+char *read_file(const char *path) {
+  char *p;
+  FILE *fp;
+  int buflen, nread, end, n;
+  if (!strcmp(path, "-")) {
+    fp = stdin;
+  } else {
+    fp = fopen(path, "r");
+    if (!fp) return NULL;
+  }
+  buflen = 4096;
+  nread = 0;
+  p = calloc(1, buflen);
+  for (;;) {
+    end = buflen - 2;
+    n = fread(p + nread, 1, end - nread, fp);
+    if (n == 0) break;
+    nread += n;
+    if (nread == end) {
+      buflen *= 2;
+      p = realloc(p, buflen);
+    }
+  }
+  if (fp != stdin) fclose(fp);
+  if (nread > 0 && p[nread - 1] == '\\') {
+    p[nread - 1] = '\n';
+  } else if (nread == 0 || p[nread - 1] != '\n') {
+    p[nread++] = '\n';
+  }
+  p[nread] = '\0';
+  return p;
+}
+
+char *skip_bom(char *p) {
+  // UTF-8 texts may start with a 3-byte "BOM" marker sequence.
+  // If exists, just skip them because they are useless bytes.
+  // (It is actually not recommended to add BOM markers to UTF-8
+  // texts, but it's not uncommon particularly on Windows.)
+  if (!memcmp(p, "\357\273\277", 3)) p += 3;
+  return p;
+}
+
+// Replaces \r or \r\n with \n.
+void canonicalize_newline(char *p) {
+  int i = 0, j = 0;
+  while (p[i]) {
+    if (p[i] == '\r' && p[i + 1] == '\n') {
+      i += 2;
+      p[j++] = '\n';
+    } else if (p[i] == '\r') {
+      i++;
+      p[j++] = '\n';
+    } else {
+      p[j++] = p[i++];
+    }
+  }
+  p[j] = '\0';
+}
+
+// Removes backslashes followed by a newline.
+void remove_backslash_newline(char *p) {
+  int i = 0, j = 0;
+  // We want to keep the number of newline characters so that
+  // the logical line number matches the physical one.
+  // This counter maintain the number of newlines we have removed.
+  int n = 0;
+  bool instring = false;
+  while (p[i]) {
+    if (instring) {
+      if (p[i] == '"' && p[i - 1] != '\\') {
+        instring = false;
+      }
+    } else {
+      if (p[i] == '"') {
+        instring = true;
+      } else if (p[i] == '/' && p[i + 1] == '*') {
+        p[j++] = p[i++];
+        p[j++] = p[i++];
+        while (p[i]) {
+          if (p[i] == '*' && p[i + 1] == '/') {
+            p[j++] = p[i++];
+            p[j++] = p[i++];
+            break;
+          } else {
+            p[j++] = p[i++];
+          }
+        }
+        continue;
+      }
+    }
+    if (p[i] == '\\' && p[i + 1] == '\n') {
+      i += 2;
+      n++;
+    } else if (p[i] == '\n') {
+      p[j++] = p[i++];
+      for (; n > 0; n--) p[j++] = '\n';
+    } else {
+      p[j++] = p[i++];
+    }
+  }
+  for (; n > 0; n--) p[j++] = '\n';
+  p[j] = '\0';
+}