dedent.hpp

Compile‑time string dedentation.

Usage

Example

#include <iostream>
#include "dedent.hpp"

int main() {
    constexpr auto code = d::dedent(R"(
        int main() {
            return 0;
        }
    )");
    std::cout << d::sv(code);
}

Output

int main() {
    return 0;
}

Custom Tab Width

// Treat a tab as advancing to the next multiple of 2 columns
constexpr auto text = d::dedent<2>(R"(
	First line
		Indented line
)");

Handling Blank Lines

• Blank lines at the very beginning and end of the input (containing only spaces, tabs, \r, \f, or \v) are removed entirely.
• Internal blank lines are preserved as a single line break: \n for LF input, \r\n for CRLF input.

constexpr auto poem = d::dedent(R"(

    Roses are red,
    Violets are blue,

    Sugar is sweet,
    And so are you.

)");
// Resulting string_view content:
// "Roses are red,\nViolets are blue,\n\nSugar is sweet,\nAnd so are you.\n"

API Reference

d::dedent<size_t TabWidth = 4>(const char (&in)[N])

Purpose

Compile‑time dedentation of the raw string literal in, also trimming surrounding blank lines.

Template Parameter

TabWidth: tab stop distance in columns. A \t advances to the next multiple of TabWidth. Tabs are never partially removed, so with mixed space/tab indentation a tab may be kept even when the spaces before it are trimmed. Defaults to 4.

Return Value

std::array<char, N> where N is the size of the input literal (including its terminating '\0'). The dedented text starts at index 0, is terminated by '\0', and the rest of the array is zero‑filled. Use d::sv to obtain a std::string_view of the dedented text.

Bind the result to a named variable before calling d::sv; d::sv(d::dedent(...)) is rejected at compile time because the view would refer to a temporary array:

constexpr auto code = d::dedent(R"(...)");
constexpr auto view = d::sv(code);  // ok

d::sv(const std::array<char, N>& a)

Purpose

Converts the array returned by dedent into a std::string_view for convenient output or further processing. The rvalue overload is deleted, so a view into a temporary array cannot be created by accident.

Return Value std::string_view covering the dedented string (excluding the null terminator).

Implementation Details

The library uses internal helper functions inside the d::dt namespace, all of which are constexpr:

• is_space(char): Checks whether a character is ' ', '\t', '\r', '\f', or '\v'.
• width<TabWidth>(col, char): Returns the visual width of a leading‑whitespace character at column col (a \t advances to the next multiple of TabWidth), or a sentinel for any character that ends the leading whitespace run.
• leading_width<TabWidth>(string_view): Computes the total visual width of a line's leading whitespace.
• is_blank(string_view): Determines if a line contains only whitespace.
• chars_to_skip<TabWidth>(string_view, max_width): Returns the number of leading characters to skip so the remaining visual width does not exceed max_width.

Requirements

• C++17 or later (uses std::string_view, enhanced constexpr, etc.).
• Built and tested in CI with GCC, Clang, AppleClang, and MSVC (see .github/workflows/ci.yml).

License

This project is licensed under the MIT License. See the LICENSE file for details.