67 lines
2.2 KiB
Zig
67 lines
2.2 KiB
Zig
//
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// ------------------------------------------------------------
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// TOP SECRET TOP SECRET TOP SECRET TOP SECRET TOP SECRET
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// ------------------------------------------------------------
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//
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// Are you ready for the THE TRUTH about Zig string literals?
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//
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// Here it is:
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//
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// @TypeOf("foo") == *const [3:0]u8
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//
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// Which means a string literal is a "constant pointer to a
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// zero-terminated (null-terminated) fixed-size array of u8".
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//
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// Now you know. You've earned it. Welcome to the secret club!
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//
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// ------------------------------------------------------------
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//
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// Why do we bother using a zero/null sentinel to terminate
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// strings in Zig when we already have a known length?
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//
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// Versatility! Zig strings are compatible with C strings (which
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// are null-terminated) AND can be coerced to a variety of other
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// Zig types:
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//
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// const a: [5]u8 = "array".*;
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// const b: *const [16]u8 = "pointer to array";
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// const c: []const u8 = "slice";
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// const d: [:0]const u8 = "slice with sentinel";
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// const e: [*:0]const u8 = "many-item pointer with sentinel";
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// const f: [*]const u8 = "many-item pointer";
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//
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// All but 'f' may be printed. (A many-item pointer without a
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// sentinel is not safe to print because we don't know where it
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// ends!)
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//
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const print = @import("std").debug.print;
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const WeirdContainer = struct {
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data: [*]const u8,
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length: usize,
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};
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pub fn main() void {
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// WeirdContainer is an awkward way to house a string.
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//
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// Being a many-item pointer (with no sentinel termination),
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// the 'data' field "loses" the length information AND the
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// sentinel termination of the string literal "Weird Data!".
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//
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// Luckily, the 'length' field makes it possible to still
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// work with this value.
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const foo = WeirdContainer{
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.data = "Weird Data!",
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.length = 11,
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};
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// How do we get a printable value from 'foo'? One way is to
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// turn it into something with a known length. We do have a
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// length... You've actually solved this problem before!
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//
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// Here's a big hint: do you remember how to take a slice?
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const printable = foo.data[0..foo.length];
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print("{s}\n", .{printable});
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}
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