Vix.cpp

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String helpers (vix::utils::String) ​

Small, header-only utilities for common string operations used across Vix.cpp: trim, case transforms, prefix/suffix checks, split/join, and a few HTTP helpers (boundary extraction, URL decode, query string parsing).

Source file: String.hpp

Include ​

cpp
#include <vix/utils/String.hpp>

Namespace:

cpp
using namespace vix::utils;

What this file provides ​

Whitespace and trim (ASCII whitespace) ​

  • ltrim(std::string s) noexcept -> std::string
  • rtrim(std::string s) noexcept -> std::string
  • trim(std::string s) noexcept -> std::string

These functions operate on a copy of the input string and return by value. This is convenient for chaining:

cpp
#include <vix/utils/String.hpp>

std::string cleaned()
{
  std::string s = "   hello  ";
  return vix::utils::trim(std::move(s)); // "hello"
}

Whitespace check is intentionally ASCII-focused via _is_space(): space + \t \n \v \f \r.

Case transform ​

Lowercase (ASCII, C locale) ​

  • to_lower(std::string s) noexcept -> std::string

This is byte-wise ASCII lowering. It is not Unicode case folding.

cpp
#include <vix/utils/String.hpp>

std::string key_normalize(std::string s)
{
  return vix::utils::to_lower(vix::utils::trim(std::move(s)));
}

Prefix and suffix checks ​

  • starts_with(std::string_view s, std::string_view p) noexcept -> bool
  • ends_with(std::string_view s, std::string_view p) noexcept -> bool
cpp
#include <vix/utils/String.hpp>

bool is_json(std::string_view p)
{
  return vix::utils::ends_with(p, ".json");
}

bool is_vix_module(std::string_view name)
{
  return vix::utils::starts_with(name, "vix");
}

Case-insensitive prefix ​

  • starts_with_icase(std::string_view s, std::string_view prefix) -> bool

ASCII-only, predictable, fast.

cpp
#include <vix/utils/String.hpp>

bool has_bearer(std::string_view header)
{
  return vix::utils::starts_with_icase(header, "bearer ");
}

Split and join ​

Split by a single character ​

  • split(std::string_view s, char sep) -> std::vector<std::string>

Keeps empty segments.

cpp
#include <vix/utils/String.hpp>

std::vector<std::string> parts()
{
  // ["a","b","","c"]
  return vix::utils::split("a,b,,c", ',');
}

Split by a string separator ​

  • split(std::string_view s, std::string_view sep) -> std::vector<std::string>

Keeps empty segments. If sep is empty, no split is performed (returns {s}).

cpp
#include <vix/utils/String.hpp>

std::vector<std::string> parts()
{
  // ["a","b","","c"]
  return vix::utils::split("a--b----c", "--");
}

Join ​

  • join(const std::vector<std::string>& v, std::string_view sep) -> std::string

Pre-reserves capacity for fewer reallocations.

cpp
#include <vix/utils/String.hpp>

std::string build()
{
  std::vector<std::string> v = {"a","b","","c"};
  return vix::utils::join(v, "::"); // "a::b::::c"
}

HTTP helpers ​

Extract multipart boundary ​

  • extract_boundary(std::string_view content_type) -> std::string

Parses strings like:

  • multipart/form-data; boundary=----WebKitFormBoundaryabc
  • multipart/form-data; boundary="----abc"
cpp
#include <vix/utils/String.hpp>

std::string boundary_from_header(std::string_view ct)
{
  return vix::utils::extract_boundary(ct);
}

URL decode ​

  • url_decode(std::string_view in) -> std::string

Rules:

  • + becomes space
  • %XX hex sequences are decoded
  • invalid % sequences are left as-is
cpp
#include <vix/utils/String.hpp>

std::string decode_demo()
{
  return vix::utils::url_decode("q=hello%20world+vix"); // "q=hello world vix"
}

Query string parsing ​

  • parse_query_string(std::string_view qs) -> std::unordered_map<std::string, std::string>

Parses key/value pairs separated by &. Keys and values are URL-decoded. If a key appears multiple times, the last one wins (map overwrite).

cpp
#include <vix/utils/String.hpp>

std::unordered_map<std::string, std::string> parse()
{
  // { "q": "hello world", "page": "2" }
  return vix::utils::parse_query_string("q=hello%20world&page=2");
}

Notes and constraints ​

  • All helpers are ASCII/byte-oriented by design (predictable, fast, no locale surprises).
  • split keeps empty segments (this is intentional, useful for parsers).
  • Query parsing uses std::unordered_map, so ordering is not preserved.

File location suggestion (project) ​

If this is part of the utils module, keep it under:

txt
modules/utils/include/vix/utils/String.hpp