### D - std.algorithm.sorting Examples

Source: https://context7.com/dlang/phobos/llms.txt

Illustrates sorting and partitioning functions including `sort`, `schwartzSort`, `multiSort`, `topN`, `partition`, and `isSorted`. Requires imports from `std.algorithm.sorting`, `std.algorithm.iteration`, `std.array`, and `std.stdio`.

```d
import std.algorithm.sorting;
import std.algorithm.iteration : map;
import std.array : array;
import std.stdio;

void main()
{
    // Basic in-place sort (returns SortedRange)
    int[] a = [5, 3, 8, 1, 4];
    sort(a);
    writeln(a);             // [1, 3, 4, 5, 8]

    // Custom comparator (descending)
    sort!"a > b"(a);
    writeln(a);             // [8, 5, 4, 3, 1]

    // schwartzSort: sort by computed key without redundant evaluation
    string[] words = ["banana", "kiwi", "apple", "fig"];
    schwartzSort!(w => w.length)(words);
    writeln(words);         // ["fig", "kiwi", "apple", "banana"]

    // multiSort: sort by multiple keys
    auto students = [
        ["Alice", "B"], ["Bob", "A"], ["Charlie", "B"], ["Dave", "A"]
    ];
    multiSort!("a[1] < b[1]", "a[0] < b[0]")(students);
    writeln(students);      // [["Bob","A"],["Dave","A"],["Alice","B"],["Charlie","B"]]

    // topN: partially sorts so first n elements are the n smallest
    int[] b = [5, 3, 8, 1, 4, 2];
    topN(b, 3);
    writeln(b[0 .. 3]);     // some permutation of [1, 2, 3]

    // isSorted check
    assert(isSorted([1, 2, 3, 4]));
    assert(!isSorted([1, 3, 2]));

    // partition: split in-place by predicate
    int[] c = [1, 2, 3, 4, 5, 6];
    auto mid = partition!(x => x % 2 == 0)(c);
    writeln(c);             // even elements at front, odd at back (order unspecified)
}

```

--------------------------------

### D - std.algorithm.searching Examples

Source: https://context7.com/dlang/phobos/llms.txt

Demonstrates various searching functions like `all`, `any`, `canFind`, `count`, `find`, `findSplit`, `startsWith`, `endsWith`, `minElement`, `maxElement`, `minIndex`, `maxIndex`, and `commonPrefix`. Ensure `std.algorithm.searching` and `std.stdio` are imported.

```d
import std.algorithm.searching;
import std.stdio;

void main()
{
    int[] data = [3, 1, 4, 1, 5, 9, 2, 6];

    // Test predicates over entire range
    assert(all!"a > 0"(data));
    assert(any!"a > 8"(data));

    // canFind with value or predicate
    assert(canFind(data, 5));
    assert(canFind!"a > 8"(data));

    // count occurrences
    writeln(count(data, 1));              // 2
    writeln(count!"a > 4"(data));         // 3

    // find returns suffix starting at match
    auto r = find(data, 5);
    writeln(r);                           // [5, 9, 2, 6]

    // findSplit splits into three parts
    auto parts = findSplit(data, [1, 5]);
    writeln(parts[0]);                    // [3, 1, 4]
    writeln(parts[1]);                    // [1, 5]
    writeln(parts[2]);                    // [9, 2, 6]

    // min/max element and index
    writeln(minElement(data));            // 1
    writeln(maxElement(data));            // 9
    writeln(minIndex(data));              // 1
    writeln(maxIndex(data));              // 5

    // startsWith / endsWith
    assert(startsWith("hello world", "hello"));
    assert(endsWith("hello world", "world"));

    // commonPrefix
    import std.algorithm.searching : commonPrefix;
    writeln(commonPrefix("parakeet", "parachute")); // para
}

```

--------------------------------

### Type Conversion with std.conv

Source: https://context7.com/dlang/phobos/llms.txt

Shows how to convert between different types using `to` and `parse`. Includes examples of converting to integers with different radices, handling conversion errors, and using `text` for concatenation.

```d
import std.conv;
import std.stdio;

void main()
{
    // to!T: convert any type to T
    int i   = to!int("42");
    double d = to!double("3.14");
    string s = to!string(255);
    writeln(i, " ", d, " ", s);    // 42 3.14 255

    // to with radix
    int hex = to!int("FF", 16);
    writeln(hex);                  // 255

    // ConvException on bad input
    try
        to!int("abc");
    catch (ConvException e)
        writeln("Error: ", e.msg);

    // text(): concatenate multiple values into a string
    writeln(text("x=", 42, " y=", 3.14));  // x=42 y=3.14

    // parse: consume from front of input range
    string input = "123abc";
    int n = parse!int(input);
    writeln(n, " remaining: ", input);     // 123 remaining: abc

    // toChars: lazy digits without allocation
    import std.algorithm.comparison : equal;
    assert(equal(toChars(42), "42"));

    // Hex string literal helper
    auto bytes = hexString!"DEADBEEF";
    writeln(bytes.length);  // 4

    // octal literal helper
    writeln(octal!755);     // 493

    // signed / unsigned narrowing casts with overflow check
    writeln(signed(cast(ubyte) 200));   // -56 (wraps as byte)
}

```

--------------------------------

### Date, Time, and Duration Operations in D

Source: https://context7.com/dlang/phobos/llms.txt

Illustrates how to work with dates, times, and durations, including getting the current time, constructing date/time objects, performing arithmetic, and using StopWatch for benchmarking. Requires importing std.datetime, std.stdio, and core.time.

```d
import std.datetime;
import std.stdio;
import core.time : seconds, minutes, hours, days, msecs;

void main()
{
    // Current time
    SysTime now = Clock.currTime();
    writeln("Now: ", now);
    writeln("UTC: ", Clock.currTime(UTC()));

    // Construct Date / DateTime
    auto birthday = Date(1990, 6, 15);
    auto meeting  = DateTime(2024, 6, 15, 14, 30, 0);
    writeln(birthday);  // 1990-Jun-15
    writeln(meeting);   // 2024-Jun-15T14:30:00

    // Arithmetic with Duration
    auto tomorrow = now + days(1);
    auto lastWeek = now - days(7);
    writeln("Tomorrow: ", tomorrow.toSimpleString);

    // Duration construction and arithmetic
    auto dur1 = hours(2) + minutes(30) + seconds(15);
    writeln(dur1.total!("seconds"));  // 9015

    // Date component access
    writeln(birthday.year, "/", birthday.month, "/", birthday.day);
    writeln(birthday.dayOfWeek);
    writeln(birthday.dayOfYear);

    // Interval: range of time
    auto interval = Interval!SysTime(now, now + days(30));
    assert(interval.contains(now + days(5)));

    // StopWatch: benchmarking
    auto sw = StopWatch(AutoStart.yes);
    import core.thread : Thread;
    Thread.sleep(msecs(50));
    sw.stop();
    writeln("Elapsed: ", sw.peek.total!"msecs", " ms");

    // Parsing ISO string
    auto parsed = SysTime.fromISOExtString("2024-06-15T12:00:00Z");
    writeln(parsed.toISOExtString);  // 2024-06-15T12:00:00Z
}
```

--------------------------------

### std.datetime — Dates, Times, and Durations

Source: https://context7.com/dlang/phobos/llms.txt

Provides examples for working with dates, times, and durations using the `std.datetime` module. Covers current time retrieval, construction of date/time objects, arithmetic operations, and benchmarking with `StopWatch`.

```APIDOC
## std.datetime — Dates, Times, and Durations

### std.datetime — SysTime, Date, Duration, StopWatch, Clock

Key symbols: `Date`, `TimeOfDay`, `DateTime`, `SysTime`, `Clock`, `Duration`, `StopWatch`, `Interval`.

### Description
This section demonstrates how to use the `std.datetime` module for handling dates, times, and durations. It includes examples for getting the current time, creating date and time objects, performing arithmetic with durations, and using `StopWatch` for benchmarking.

### Current Time

#### `Clock.currTime`
```d
import std.datetime;
import std.stdio;

SysTime now = Clock.currTime();
writeln("Now: ", now);
writeln("UTC: ", Clock.currTime(UTC()));
```

### Constructing Date and DateTime

#### `Date` and `DateTime` constructors
```d
import std.datetime;
import std.stdio;

auto birthday = Date(1990, 6, 15);
auto meeting  = DateTime(2024, 6, 15, 14, 30, 0);
writeln(birthday);  // 1990-Jun-15
writeln(meeting);   // 2024-Jun-15T14:30:00
```

### Arithmetic with Duration

#### Adding and subtracting `Duration`
```d
import std.datetime;
import std.stdio;
import core.time : days;

SysTime now = Clock.currTime();
auto tomorrow = now + days(1);
auto lastWeek = now - days(7);
writeln("Tomorrow: ", tomorrow.toSimpleString);
```

### Duration Construction and Arithmetic

#### `Duration` examples
```d
import std.datetime;
import core.time : hours, minutes, seconds;

auto dur1 = hours(2) + minutes(30) + seconds(15);
writeln(dur1.total!"seconds");  // 9015
```

### Date Component Access

#### Accessing year, month, day, etc.
```d
import std.datetime;
import std.stdio;

auto birthday = Date(1990, 6, 15);
writeln(birthday.year, "/", birthday.month, "/", birthday.day);
writeln(birthday.dayOfWeek);
writeln(birthday.dayOfYear);
```

### Interval: Range of Time

#### `Interval` usage
```d
import std.datetime;
import core.time : days;

SysTime now = Clock.currTime();
auto interval = Interval!SysTime(now, now + days(30));
assert(interval.contains(now + days(5)));
```

### StopWatch: Benchmarking

#### `StopWatch` usage
```d
import std.datetime;
import core.time : msecs;
import core.thread : Thread;

auto sw = StopWatch(AutoStart.yes);
Thread.sleep(msecs(50));
sw.stop();
writeln("Elapsed: ", sw.peek.total!"msecs", " ms");
```

### Parsing ISO String

#### `SysTime.fromISOExtString`
```d
import std.datetime;

auto parsed = SysTime.fromISOExtString("2024-06-15T12:00:00Z");
writeln(parsed.toISOExtString);  // 2024-06-15T12:00:00Z
```
```

--------------------------------

### D std.math Module Examples

Source: https://context7.com/dlang/phobos/llms.txt

Demonstrates various mathematical functions and constants available in the std.math module, including algebraic, exponential, trigonometric, and rounding operations, as well as special value checks and power-of-two calculations. Requires importing std.math and std.stdio.

```d
import std.math;
import std.stdio;

void main()
{
    // Constants
    writeln(PI);		// 3.14159...
    writeln(E);		// 2.71828...
    writeln(SQRT2);		// 1.41421...
    writeln(LN2);		// 0.69315...

    // Algebraic
    writeln(abs(-42));			// 42
    writeln(sqrt(2.0));			// 1.41421...
    writeln(cbrt(27.0));			// 3.0
    writeln(hypot(3.0, 4.0));		// 5.0
    writeln(pow(2.0, 10));			// 1024.0

    // Exponential / Logarithm
    writeln(exp(1.0));			// 2.71828...
    writeln(log(E));			// 1.0
    writeln(log2(1024.0));			// 10.0
    writeln(log10(1000.0));			// 3.0

    // Trigonometry
    writeln(sin(PI / 6));			// ~0.5
    writeln(cos(0.0));			// 1.0
    writeln(atan2(1.0, 1.0));		// PI/4 ≈ 0.7854

    // Rounding
    writeln(ceil(1.3));			// 2.0
    writeln(floor(1.9));			// 1.0
    writeln(round(1.5));			// 2.0
    writeln(trunc(-3.9));			// -3.0

    // Special value checks
    assert( isNaN(real.nan));
    assert( isInfinity(1.0 / 0.0));
    assert(!isNaN(3.14));
    assert( isFinite(3.14));

    // nextPow2 / truncPow2
    writeln(nextPow2(100));		// 128
    writeln(truncPow2(100));		// 64
}

```

--------------------------------

### Add New Changelog Entry

Source: https://github.com/dlang/phobos/blob/master/changelog/README.md

Create a new file ending in .dd in the changelog folder. The first line is the title, followed by an empty line and then the long description. Code examples can be included within the description, separated by '-------'.

```dd
My fancy title of the new feature

A long description of the new feature in `std.range`.
It can be followed by an example:
-------
import std.range : padLeft, padRight;
import std.algorithm.comparison : equal;

assert([1, 2, 3, 4, 5].padLeft(0, 7).equal([0, 0, 1, 2, 3, 4, 5]));

assert("Hello World!".padRight('!', 15).equal("Hello World!!!!"));
-------
```

--------------------------------

### File System Operations with std.file

Source: https://context7.com/dlang/phobos/llms.txt

Covers essential file system operations including reading, writing, appending, checking existence and type, getting file metadata, copying, renaming, and directory manipulation. It also demonstrates iterating through directory entries and slurping file content into typed rows.

```d
import std.file;
import std.stdio;
import std.path : buildPath;

void main()
{
    // write and read a text file
    write("hello.txt", "Hello, Phobos!\n");
    string content = readText("hello.txt");
    writeln(content);   // Hello, Phobos!

    // append
    append("hello.txt", "Second line\n");

    // existence and type checks
    assert(exists("hello.txt"));
    assert(isFile("hello.txt"));

    // file metadata
    writeln("size: ", getSize("hello.txt"));

    // copy and rename
    copy("hello.txt", "hello2.txt");
    rename("hello2.txt", "hello_renamed.txt");

    // directory operations
    mkdirRecurse("mydir/sub");
    write(buildPath("mydir", "sub", "data.txt"), "nested file");
    assert(isDir("mydir/sub"));

    // dirEntries: iterate a directory tree
    foreach (DirEntry e; dirEntries("mydir", SpanMode.depth))
        writeln(e.isDir ? "[dir]  " : "[file] ", e.name);

    // slurp: read file into array of typed rows
    write("data.csv", "1 Alice\n2 Bob\n3 Charlie\n");
    auto rows = slurp!(int, string)("data.csv", "%d %s");
    foreach (row; rows)
        writefln("id=%d name=%s", row[0], row[1]);

    // cleanup
    rmdirRecurse("mydir");
    remove("hello.txt");
    remove("hello_renamed.txt");
    remove("data.csv");
}
```

--------------------------------

### Symbol Definitions

Source: https://github.com/dlang/phobos/blob/master/etc/c/zlib/doc/algorithm.txt

Defines the symbols and their corresponding bit codes used in the deflate algorithm example. These are the codes that the inflate process will decode.

```text
A: 0
B: 10
C: 1100
D: 11010
E: 11011
F: 11100
G: 11101
H: 11110
I: 111110
J: 111111
```

--------------------------------

### Basic Output and File Operations with std.stdio

Source: https://context7.com/dlang/phobos/llms.txt

Demonstrates basic console output functions like writeln, write, and writefln. Also shows how to open, write to, and read from files line by line or in chunks using the File type and its associated methods.

```d
import std.stdio;

void main()
{
    // Basic output
    writeln("Hello, World!");
    write("no newline ");
    writefln("formatted %d", 42);

    // File: open, read line by line
    auto f = File("data.txt", "w");
    f.writeln("line one");
    f.writeln("line two");
    f.writeln("line three");
    f.close();

    // Read all lines lazily
    foreach (line; File("data.txt").byLine)
        writeln("> ", line);

    // Read fixed-size chunks
    foreach (chunk; File("data.txt").byChunk(16))
        writeln("chunk: ", cast(string) chunk);

    // lines() helper: reads entire file into array of lines
    import std.file : write;
    write("nums.txt", "10\n20\n30\n");
    foreach (i, line; lines(File("nums.txt")))
        writefln("line %d: %s", i, line.chomp);

    // readln from stdin (interactive)
    // string userInput = readln();

    // stderr for diagnostics
    stderr.writeln("This goes to stderr");

    // readf: formatted scan from stdin
    // int x; readf(" %d", x);
}
```

--------------------------------

### Table X (2 bits)

Source: https://github.com/dlang/phobos/blob/master/etc/c/zlib/doc/algorithm.txt

The second-level lookup table, referenced from the first table. This table handles symbols that start with '110' and are longer than 3 bits.

```text
00: C,1
01: C,1
10: D,2
11: E,2
```

--------------------------------

### Printf-style Formatting with std.format

Source: https://context7.com/dlang/phobos/llms.txt

Illustrates using `format`, `sformat`, and `formattedWrite` for creating formatted strings. Covers format specifiers for width, precision, fill, and different bases, as well as parsing formatted strings with `formattedRead`.

```d
import std.format;
import std.array : appender;
import std.stdio;

void main()
{
    // format: returns a newly allocated string
    string s = format("Hello, %s! You are %d years old.", "Alice", 30);
    writeln(s);     // Hello, Alice! You are 30 years old.

    // format specifiers: width, precision, fill
    writeln(format("%10d", 42));          // "        42"
    writeln(format("% -10s|", "left"));    // "left      |"
    writeln(format("%08.2f", 3.14));      // "00003.14"
    writeln(format("%x", 255));           // "ff"
    writeln(format("%X", 255));           // "FF"
    writeln(format("%b", 12));            // "1100"

    // format arrays and structs
    writeln(format("%s", [1, 2, 3]));     // [1, 2, 3]

    // sformat: write into a provided char buffer (no allocation)
    char[64] buf;
    auto filled = sformat(buf[], "pi = %.4f", 3.14159);
    writeln(filled);    // pi = 3.1416

    // formattedWrite: write to any output range (e.g., Appender)
    auto app = appender!string;
    formattedWrite(app, "(%d, %d)", 10, 20);
    writeln(app.data);  // (10, 20)

    // formattedRead: parse values from a formatted string
    string input = "name=Bob age=25";
    string name;
    int age;
    formattedRead(input, "name=%s age=%d", name, age);
    writeln(name, " is ", age);  // Bob is 25
}

```

--------------------------------

### Table Y (3 bits)

Source: https://github.com/dlang/phobos/blob/master/etc/c/zlib/doc/algorithm.txt

Another second-level lookup table, referenced from the first table. This table handles symbols that start with '111' and are longer than 3 bits.

```text
000: F,2
001: F,2
010: G,2
011: G,2
100: H,2
101: H,2
110: I,3
111: J,3
```

--------------------------------

### Dlang Data Parallelism with std.parallelism

Source: https://context7.com/dlang/phobos/llms.txt

Illustrates parallel processing of arrays using foreach, lazy mapping, and reduction operations with std.parallelism. Also shows manual task creation and custom TaskPool usage.

```d
import std.parallelism;
import std.algorithm.iteration : map;
import std.math : sqrt;
import std.range : iota;
import std.array : array;
import std.stdio;

void main()
{
    // parallel foreach: process array items across CPU cores
    auto data = iota(1, 9).array;
    auto results = new double[data.length];
    foreach (i, ref val; parallel(data))
        results[i] = sqrt(cast(double) val);
    writeln(results);

    // taskPool.map: parallel lazy map
    auto arr = iota(0, 10_000).array;
    auto sums = taskPool.map!(x => x * x)(arr);
    writeln(sums[0 .. 5]);  // [0, 1, 4, 9, 16]

    // taskPool.reduce: parallel reduction
    auto total = taskPool.reduce!"a + b"(0.0, arr.map!(x => cast(double) x));
    writeln("sum = ", total);  // 49995000.0

    // Manual task with future/promise pattern
    auto t = task!(() => 6 * 7)();
    taskPool.put(t);
    writeln("6 * 7 = ", t.yieldForce);  // 42

    // Custom TaskPool with explicit thread count
    auto pool = new TaskPool(4);
    scope(exit) pool.finish(true);
    foreach (i; pool.parallel(iota(5).array))
        writeln("processing ", i);
}
```

--------------------------------

### std.algorithm.searching

Source: https://context7.com/dlang/phobos/llms.txt

Provides functions for searching ranges, including checking for element existence, counting occurrences, finding elements, splitting ranges, and determining if a range starts or ends with a specific sequence.

```APIDOC
## std.algorithm.searching — Find, Count, and Test Elements

### Description
Functions for searching ranges: `all`, `any`, `canFind`, `count`, `find`, `findSplit`, `startsWith`, `endsWith`, `minElement`, `maxElement`, `minIndex`, `maxIndex`, and more.

### Usage Examples
```d
import std.algorithm.searching;
import std.stdio;

void main()
{
    int[] data = [3, 1, 4, 1, 5, 9, 2, 6];

    // Test predicates over entire range
    assert(all!("a > 0")(data));
    assert(any!("a > 8")(data));

    // canFind with value or predicate
    assert(canFind(data, 5));
    assert(canFind!("a > 8")(data));

    // count occurrences
    writeln(count(data, 1));              // 2
    writeln(count!("a > 4")(data));         // 3

    // find returns suffix starting at match
    auto r = find(data, 5);
    writeln(r);                           // [5, 9, 2, 6]

    // findSplit splits into three parts
    auto parts = findSplit(data, [1, 5]);
    writeln(parts[0]);                    // [3, 1, 4]
    writeln(parts[1]);                    // [1, 5]
    writeln(parts[2]);                    // [9, 2, 6]

    // min/max element and index
    writeln(minElement(data));            // 1
    writeln(maxElement(data));            // 9
    writeln(minIndex(data));              // 1
    writeln(maxIndex(data));              // 5

    // startsWith / endsWith
    assert(startsWith("hello world", "hello"));
    assert(endsWith("hello world", "world"));

    // commonPrefix
    import std.algorithm.searching : commonPrefix;
    writeln(commonPrefix("parakeet", "parachute")); // para
}
```
```

--------------------------------

### Dlang Concurrency with std.concurrency

Source: https://context7.com/dlang/phobos/llms.txt

Demonstrates spawning a worker thread, sending typed messages, and receiving replies using std.concurrency. Includes named thread registration and lookup.

```d
import std.concurrency;
import std.conv : text;
import std.stdio;

// Worker function: runs in its own thread
static void worker(Tid owner)
{
    // Receive typed messages via pattern matching
    bool running = true;
    while (running)
    {
        receive(
            (int n) {
                send(owner, text("Got int: ", n));
            },
            (string s) {
                if (s == "quit")
                    running = false;
                else
                    send(owner, text("Got string: ", s));
            }
        );
    }
}

void main()
{
    Tid tid = spawn(&worker, thisTid);

    // Send messages to the worker
    send(tid, 42);
    send(tid, "hello");
    send(tid, "quit");

    // Receive replies (with timeout for safety)
    import core.time : msecs;
    foreach (_; 0 .. 2)
    {
        receiveTimeout(msecs(1000),
            (string reply) { writeln(reply); }
        );
    }
    // Got int: 42
    // Got string: hello

    // Named thread registration
    register("printer", thisTid);
    Tid found = locate("printer");
    assert(found == thisTid);
}
```

--------------------------------

### Preview Pending Changelog

Source: https://github.com/dlang/phobos/blob/master/changelog/README.md

To preview the changelog locally, clone the 'tools' and 'dlang.org' repositories and run the 'pending_changelog' make target.

```bash
make -C ../dlang.org -f posix.mak pending_changelog
```

--------------------------------

### String Manipulation with std.string

Source: https://context7.com/dlang/phobos/llms.txt

Demonstrates various string manipulation functions including stripping whitespace, finding substrings, chomping/chopping strings, justification, and character translation. Also includes C interop helpers for string conversion.

```d
import std.string;
import std.stdio;

void main()
{
    string s = "  Hello, World!  ";

    // strip whitespace
    writeln(strip(s));              // "Hello, World!"
    writeln(stripLeft(s));          // "Hello, World!  "
    writeln(stripRight(s));         // "  Hello, World!"

    // indexOf / lastIndexOf
    writeln(indexOf("hello world", "world"));    // 6
    writeln(lastIndexOf("abcabc", "bc"));        // 4

    // chomp / chop
    writeln(chomp("hello\n"));      // "hello"
    writeln(chop("hello"));         // "hell"

    // center / leftJustify / rightJustify
    writeln(center("hi", 10));          // "    hi    "
    writeln(leftJustify("hi", 10, '-')); // "hi--------"
    writeln(rightJustify("hi", 10, '-')); // "--------hi"

    // translate: character-by-character substitution table
    string from = "aeiou";
    string to   = "AEIOU";
    writeln(translate("hello world", makeTrans(from, to))); // hEllO wOrld

    // tr: POSIX-style character translation/deletion
    writeln(tr("Hello World", "a-z", "A-Z"));   // HELLO WORLD
    writeln(tr("hello 123", "0-9", "", "d"));   // hello  (delete digits)

    // wrap: word-wrap long text
    string text = "The quick brown fox jumps over the lazy dog";
    writeln(wrap(text, 20));
    // The quick brown fox
    // jumps over the lazy
    // dog

    // C interop helpers
    import core.stdc.string : strlen;
    const(char)* cstr = toStringz("hello");
    writeln(fromStringz(cstr));     // hello
}

```

--------------------------------

### Dlang Comparison Functions

Source: https://context7.com/dlang/phobos/llms.txt

Illustrates element-wise range equality (equal), finding minimum (min) and maximum (max) values, clamping a value within bounds (clamp), checking membership in a set (among), calculating edit distance (levenshteinDistance), finding the first differing pair in ranges (mismatch), and lexicographic comparison (cmp). Requires importing std.algorithm.comparison.

```d
import std.algorithm.comparison;
import std.stdio;

void main()
{
    // equal: element-wise equality (works on any ranges)
    assert(equal([1, 2, 3], [1, 2, 3]));
    assert(!equal([1, 2], [1, 2, 3]));

    // min / max of multiple values
    writeln(min(3, 1, 4, 1, 5));   // 1
    writeln(max(3, 1, 4, 1, 5));   // 5

    // clamp: bound a value within [lo, hi]
    writeln(clamp(10, 0, 5));      // 5
    writeln(clamp(-3, 0, 5));      // 0
    writeln(clamp(2, 0, 5));       // 2

    // among: check if value is in a set
    assert(among(3, 1, 2, 3, 4));

    // levenshteinDistance: edit distance between strings
    writeln(levenshteinDistance("kitten", "sitting")); // 3

    // mismatch: find first differing pair
    auto pair = mismatch([1, 2, 3, 4], [1, 2, 9, 4]);
    writeln(pair[0].front, " vs ", pair[1].front);     // 3 vs 9

    // cmp: lexicographic comparison, returns negative/0/positive
    assert(cmp([1, 2, 3], [1, 2, 4]) < 0);
    assert(cmp("abc", "abc") == 0);
}

```

--------------------------------

### Dlang std.range Functions

Source: https://context7.com/dlang/phobos/llms.txt

Demonstrates common range manipulation functions like iota, take, drop, chain, zip, enumerate, retro, stride, chunks, cycle, repeat, only, slide, and tee. Requires importing std.range and potentially other modules for specific operations.

```d
import std.range;
import std.algorithm.iteration : map;
import std.array : array;
import std.stdio;

void main()
{
    // iota: lazy numeric sequence
    writeln(iota(5).array);           // [0, 1, 2, 3, 4]
    writeln(iota(1, 10, 2).array);    // [1, 3, 5, 7, 9]

    // take / drop
    writeln(iota(100).take(5).array); // [0, 1, 2, 3, 4]
    writeln(iota(10).drop(7).array);  // [7, 8, 9]

    // chain: concatenate ranges
    writeln(chain([1, 2], [3, 4], [5]).array);  // [1, 2, 3, 4, 5]

    // zip: pair elements from multiple ranges
    auto pairs = zip([1, 2, 3], ["a", "b", "c"]).array;
    writeln(pairs);   // [Tuple!(1,"a"), Tuple!(2,"b"), Tuple!(3,"c")]

    // enumerate: (index, value) pairs
    foreach (i, v; enumerate(["x", "y", "z"]))
        writefln("%d: %s", i, v);     // 0:x, 1:y, 2:z

    // retro: reverse traversal
    writeln(retro([1, 2, 3, 4]).array);  // [4, 3, 2, 1]

    // stride: every Nth element
    writeln(stride(iota(10), 3).array);  // [0, 3, 6, 9]

    // chunks: split into fixed-size sub-ranges
    writeln(chunks([1,2,3,4,5,6,7], 3).array); // [[1,2,3],[4,5,6],[7]]

    // cycle: infinite circular range
    writeln(cycle([1, 2, 3]).take(8).array);    // [1,2,3,1,2,3,1,2]

    // repeat / only
    writeln(repeat(0, 4).array);      // [0, 0, 0, 0]
    writeln(only(10, 20, 30).array);  // [10, 20, 30]

    // slide: sliding window
    writeln(slide(iota(6), 3).array); // [[0,1,2],[1,2,3],[2,3,4],[3,4,5]]

    // tee: observe a range without consuming it
    import std.algorithm.iteration : each;
    int sum = 0;
    auto logged = tee!(x => sum += x)(iota(5));
    writeln(logged.array);   // [0,1,2,3,4]
    writeln("sum=", sum);    // sum=10
}

```

--------------------------------

### Dlang Array Utility Functions

Source: https://context7.com/dlang/phobos/llms.txt

Covers materializing ranges into dynamic arrays (array), efficient incremental string building (appender), concatenating ranges with a separator (join), splitting strings by delimiters (split), replacing substrings (replace, replaceFirst), and repeating sequences (replicate). Also demonstrates building associative arrays from key-value pairs (assocArray) and iterating them (byPair). Requires importing std.array and potentially std.range.

```d
import std.array;
import std.algorithm.iteration : map, filter;
import std.stdio;

void main()
{
    // array(): materialize any range into a dynamic array
    auto squares = map!(x => x * x)([1, 2, 3, 4, 5]).array;
    writeln(squares);           // [1, 4, 9, 16, 25]

    // appender: efficient incremental building
    auto app = appender!string();
    app.put("Hello");
    app.put(", ");
    app.put("World");
    writeln(app.data);          // Hello, World

    // appender with pre-existing array
    auto numApp = appender([1, 2, 3]);
    numApp ~= 4;
    numApp.put([5, 6]);
    writeln(numApp.data);       // [1, 2, 3, 4, 5, 6]

    // join: concatenate range of ranges with separator
    string[] words = ["one", "two", "three"];
    writeln(words.join(", "));  // one, two, three

    // split
    writeln("a,b,c".split(","));    // ["a", "b", "c"]
    writeln("hello world".split()); // ["hello", "world"] (whitespace)

    // replace / replaceFirst
    writeln("aaabbbccc".replace("bbb", "XXX"));      // aaaXXXccc
    writeln("aaabbbbbbaaa".replaceFirst("bb", "X")); // aaaXbbbbaaa

    // replicate
    writeln("ab".replicate(3));  // ababab
    writeln([1, 2].replicate(3)); // [1, 2, 1, 2, 1, 2]

    // assocArray: build AA from key/value ranges
    import std.range : zip;
    string[] keys = ["a", "b", "c"];
    int[] vals   = [1, 2, 3];
    auto aa = assocArray(zip(keys, vals));
    writeln(aa);                 // ["a":1, "b":2, "c":3]

    // byPair: iterate an AA as (key, value) tuples
    foreach (pair; aa.byPair)
        writeln(pair.key, " => ", pair.value);
}

```

--------------------------------

### Path String Manipulation with std.path

Source: https://context7.com/dlang/phobos/llms.txt

Provides utilities for OS-safe path manipulation, including building paths, extracting components (basename, dirname, extension), modifying extensions, checking path validity (absolute/relative), and performing glob-style pattern matching.

```d
import std.path;
import std.stdio;

void main()
{
    // buildPath: OS-safe path joining
    writeln(buildPath("usr", "local", "bin", "dmd"));  // usr/local/bin/dmd (Posix)

    // component extraction
    string p = "/home/user/docs/readme.txt";
    writeln(baseName(p));           // readme.txt
    writeln(dirName(p));            // /home/user/docs
    writeln(extension(p));          // .txt
    writeln(stripExtension(p));     // /home/user/docs/readme

    // setExtension / withExtension
    writeln(setExtension("file.txt", ".md"));  // file.md

    // validation
    assert(isAbsolute("/usr/bin"));
    assert(!isAbsolute("relative/path"));

    // relativePath
    writeln(relativePath("/home/user/docs/a.txt", "/home/user"));  // docs/a.txt

    // pathSplitter: iterate components
    foreach (part; pathSplitter("/usr/local/bin"))
        write("[", part, "]");
    writeln();  // [/][usr][local][bin]

    // globMatch: shell-style wildcards
    assert(globMatch("hello.d", "*.d"));
    assert(globMatch("path/to/file.txt", "**/*.txt"));
    assert(!globMatch("hello.d", "*.c"));

    // isValidPath / isValidFilename
    assert(isValidFilename("report_2024.pdf"));
}
```

--------------------------------

### Runtime and Compile-time Regex Operations in D

Source: https://context7.com/dlang/phobos/llms.txt

Demonstrates various regex operations including matching, capturing groups, replacement, and splitting using both runtime and compile-time regex. Requires importing std.regex, std.stdio, and std.array.

```d
import std.regex;
import std.stdio;
import std.array : array;

void main()
{
    // Runtime regex
    auto r = regex(`\d+`);

    // matchFirst: find first match
    auto m = matchFirst("Order #1042 and #2099", r);
    if (!m.empty)
        writeln("First number: ", m.hit);   // 1042

    // matchAll: iterate all matches
    foreach (c; matchAll("Order #1042 and #2099", r))
        writeln(c.hit);   // 1042, then 2099

    // Capture groups
    auto dateRe = regex(`(\d{4})-(\d{2})-(\d{2})`);
    auto date = matchFirst("Today is 2024-06-15", dateRe);
    writeln("Year: ", date[1], " Month: ", date[2], " Day: ", date[3]);

    // replaceFirst / replaceAll with string or delegate
    writeln(replaceAll("foo bar baz", regex(`\b\w`), m => m.hit.toUpper));
    // Foo Bar Baz

    // split by regex
    writeln(split("one1two2three", regex(`\d`)).array);  // ["one","two","three"]

    // Compile-time regex (faster, native code)
    enum ctr = ctRegex!(`^[a-z]+$`);
    assert(!matchFirst("hello", ctr).empty);
    assert(matchFirst("Hello123", ctr).empty);

    // Named captures
    auto namedRe = regex(`(?P<user>\w+)@(?P<domain>\w+\.\w+)`);
    auto email = matchFirst("contact@example.com", namedRe);
    writeln(email["user"]);    // contact
    writeln(email["domain"]);  // example.com
}
```

--------------------------------

### Dlang Lazy Iteration Functions

Source: https://context7.com/dlang/phobos/llms.txt

Demonstrates lazy transformation (map), predicate filtering (filter), left-folding with a seed (fold), summation (sum), mean calculation, eager side-effect execution (each), grouping consecutive elements (group), flattening ranges (joiner), and cumulative folding (cumulativeFold). Requires importing std.algorithm.iteration and other relevant modules.

```d
import std.algorithm.iteration;
import std.array : array;
import std.stdio;

void main()
{
    int[] data = [1, 2, 3, 4, 5, 6, 7, 8];

    // map: lazy transform
    auto doubled = map!(x => x * 2)(data);
    writeln(doubled.array);         // [2, 4, 6, 8, 10, 12, 14, 16]

    // filter: lazy predicate filter
    auto evens = filter!(x => x % 2 == 0)(data);
    writeln(evens.array);           // [2, 4, 6, 8]

    // fold: left-fold with initial seed
    auto total = fold!((a, b) => a + b)(data, 0);
    writeln(total);                 // 36

    // sum: accurate numeric summation
    writeln(sum(data));             // 36

    // mean
    writeln(mean(data));            // 4 (integer division)

    // each: eager side-effect per element
    each!(x => write(x, " "))(data);
    writeln();                      // 1 2 3 4 5 6 7 8

    // group: consecutive equal elements as (value, count) tuples
    int[] runs = [1, 1, 2, 3, 3, 3, 2];
    import std.typecons : tuple;
    writeln(group(runs).array);     // [Tuple!(1,2), Tuple!(2,1), Tuple!(3,3), Tuple!(2,1)]

    // joiner: flatten range of ranges lazily
    auto sentences = ["hello world", "foo bar"];
    import std.algorithm.iteration : splitter;
    auto words = sentences.map!(s => s.splitter(' ')).joiner;
    writeln(words.array);           // ["hello","world","foo","bar"]

    // cumulativeFold: running totals
    writeln(cumulativeFold!((a, b) => a + b)(data).array); // [1,3,6,10,15,21,28,36]
}

```