Adding code. Closes #0.

src/string_view.c

@@ -0,0 +1,163 @@
+// Copyright 2017 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "internal/string_view.h"
+
+#include <assert.h>
+#include <ctype.h>
+#include <string.h>
+
+int IndexOfChar(const StringView view, char c) {
+  if (view.ptr && view.size) {
+    const char* const found = (const char*)memchr(view.ptr, c, view.size);
+    if (found) {
+      return found - view.ptr;
+    }
+  }
+  return -1;
+}
+
+int IndexOf(const StringView view, const StringView sub_view) {
+  if (sub_view.size) {
+    StringView remainder = view;
+    while (remainder.size >= sub_view.size) {
+      const int found_index = IndexOfChar(remainder, sub_view.ptr[0]);
+      if (found_index < 0) break;
+      remainder = PopFront(remainder, found_index);
+      if (StartsWith(remainder, sub_view)) {
+        return remainder.ptr - view.ptr;
+      }
+      remainder = PopFront(remainder, 1);
+    }
+  }
+  return -1;
+}
+
+bool IsEquals(const StringView a, const StringView b) {
+  if (a.size == b.size) {
+    return a.ptr == b.ptr || memcmp(a.ptr, b.ptr, b.size) == 0;
+  }
+  return false;
+}
+
+bool StartsWith(const StringView a, const StringView b) {
+  return a.ptr && b.ptr && b.size && a.size >= b.size
+             ? memcmp(a.ptr, b.ptr, b.size) == 0
+             : false;
+}
+
+StringView PopFront(const StringView str_view, size_t count) {
+  if (count > str_view.size) {
+    return kEmptyStringView;
+  }
+  return view(str_view.ptr + count, str_view.size - count);
+}
+
+StringView PopBack(const StringView str_view, size_t count) {
+  if (count > str_view.size) {
+    return kEmptyStringView;
+  }
+  return view(str_view.ptr, str_view.size - count);
+}
+
+StringView KeepFront(const StringView str_view, size_t count) {
+  return count <= str_view.size ? view(str_view.ptr, count) : str_view;
+}
+
+char Front(const StringView view) {
+  assert(view.size);
+  assert(view.ptr);
+  return view.ptr[0];
+}
+
+char Back(const StringView view) {
+  assert(view.size);
+  return view.ptr[view.size - 1];
+}
+
+StringView TrimWhitespace(StringView view) {
+  while (view.size && isspace(Front(view))) view = PopFront(view, 1);
+  while (view.size && isspace(Back(view))) view = PopBack(view, 1);
+  return view;
+}
+
+static int HexValue(const char c) {
+  if (c >= '0' && c <= '9') return c - '0';
+  if (c >= 'a' && c <= 'f') return c - 'a' + 10;
+  if (c >= 'A' && c <= 'F') return c - 'A' + 10;
+  return -1;
+}
+
+// Returns -1 if view contains non digits.
+static int ParsePositiveNumberWithBase(const StringView view, int base) {
+  int result = 0;
+  StringView remainder = view;
+  for (; remainder.size; remainder = PopFront(remainder, 1)) {
+    const int value = HexValue(Front(remainder));
+    if (value < 0 || value >= base) return -1;
+    result = (result * base) + value;
+  }
+  return result;
+}
+
+int ParsePositiveNumber(const StringView view) {
+  if (view.size) {
+    const StringView hex_prefix = str("0x");
+    if (StartsWith(view, hex_prefix)) {
+      const StringView span_no_prefix = PopFront(view, hex_prefix.size);
+      return ParsePositiveNumberWithBase(span_no_prefix, 16);
+    }
+    return ParsePositiveNumberWithBase(view, 10);
+  }
+  return -1;
+}
+
+void CopyString(const StringView src, char* dst, size_t dst_size) {
+  if (dst_size > 0) {
+    const size_t max_copy_size = dst_size - 1;
+    const size_t copy_size =
+        src.size > max_copy_size ? max_copy_size : src.size;
+    memcpy(dst, src.ptr, copy_size);
+    dst[copy_size] = '\0';
+  }
+}
+
+bool HasWord(const StringView line, const char* const word_str) {
+  const StringView word = str(word_str);
+  StringView remainder = line;
+  for (;;) {
+    const int index_of_word = IndexOf(remainder, word);
+    if (index_of_word < 0) {
+      return false;
+    } else {
+      const StringView before = KeepFront(line, index_of_word);
+      const StringView after = PopFront(line, index_of_word + word.size);
+      const bool valid_before = before.size == 0 || Back(before) == ' ';
+      const bool valid_after = after.size == 0 || Front(after) == ' ';
+      if (valid_before && valid_after) return true;
+      remainder = PopFront(remainder, index_of_word + word.size);
+    }
+  }
+  return false;
+}
+
+bool GetAttributeKeyValue(const StringView line, StringView* key,
+                          StringView* value) {
+  const StringView sep = str(": ");
+  const int index_of_separator = IndexOf(line, sep);
+  if (index_of_separator < 0) return false;
+  *value = TrimWhitespace(PopFront(line, index_of_separator + sep.size));
+  *key = TrimWhitespace(KeepFront(line, index_of_separator));
+  return true;
+}