string_view

Overview

estd::string_view is a lightweight alternative to estd::string. It serves as a non-owning, read-only view of a string. Unlike estd::string, it does not manage the underlying memory but instead provides a reference to an existing string. estd::string_view is commonly used when you want to efficiently process and operate on strings without modifying them. It also offers functions like begin(), operator[], data(), remove_prefix() etc.

It also contains a special struct named as string_view_tokens which works over tokens of a string_view with given a set of delimiters.

Usage

The usage constraints and guidelines apply for string_view.

Usage guidance

While using functions like operator[], at(), copy() and substr(), if the index passed to the functions is outside the bounds will result in a runtime error.

The index ranges for estd::string_view starts from 0 to size() - 1.

Example

The below code shows how operator=() assigns values to the string.

estd::string_view view;
estd::string_view view2("Hello");

view = view2;
ASSERT_EQ('H', view[0]);
ASSERT_EQ('e', view[1]);
ASSERT_EQ(5U, view.size());

The below code shows the swapping of two views.

estd::string_view view  = estd::string_view("Hello");
estd::string_view view2 = estd::string_view("Jellow");

ASSERT_EQ('H', view[0]);
ASSERT_EQ('e', view[1]);
ASSERT_EQ(5U, view.size());

ASSERT_EQ('J', view2[0]);
ASSERT_EQ('e', view2[1]);
ASSERT_EQ(6U, view2.size());

view.swap(view2);

ASSERT_EQ('H', view2[0]);
ASSERT_EQ('e', view2[1]);
ASSERT_EQ(5U, view2.size());

ASSERT_EQ('J', view[0]);
ASSERT_EQ('e', view[1]);
ASSERT_EQ(6U, view.size());

The piece of code shows how the string_view can be used for tokenization.

    estd::string_view view   = estd::string_view("Hello World how is it going?");
    estd::string_view delims = estd::string_view(" ");
    estd::string_view expected_tokens[]
        = {estd::string_view("Hello"),
           estd::string_view("World"),
           estd::string_view("how"),
           estd::string_view("is"),
           estd::string_view("it"),
           estd::string_view("going?")};

    auto tokens = view.tokenize(delims);
    auto it     = tokens.begin();

    ASSERT_EQ(*it, expected_tokens[0]);
    ++it;
    ASSERT_EQ(*it, expected_tokens[1]);
    ++it;
    ASSERT_EQ(*it, expected_tokens[2]);
    ++it;
    ASSERT_EQ(*it, expected_tokens[3]);
    ++it;
    ASSERT_EQ(*it, expected_tokens[4]);
    ++it;
    ASSERT_EQ(*it, expected_tokens[5]);
    ++it;
    ASSERT_TRUE(it == tokens.end());