55 lines
1.8 KiB
Zig
55 lines
1.8 KiB
Zig
//
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// There have been several instances where it would have been
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// nice to use loops in our programs, but we couldn't because the
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// things we were trying to do could only be done at compile
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// time. We ended up having to do those things MANUALLY, like
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// NORMAL people. Bah! We are PROGRAMMERS! The computer should be
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// doing this work.
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//
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// An 'inline for' is performed at compile time, allowing you to
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// programatically loop through a series of items in situations
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// like those mentioned above where a regular runtime 'for' loop
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// wouldn't be allowed:
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//
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// inline for (.{ u8, u16, u32, u64 }) |T| {
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// print("{} ", .{@typeInfo(T).Int.bits});
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// }
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//
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// In the above example, we're looping over a list of types,
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// which are available only at compile time.
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//
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const print = @import("std").debug.print;
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// Remember Narcissus from exercise 065 where we used builtins
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// for reflection? He's back and loving it.
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const Narcissus = struct {
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me: *Narcissus = undefined,
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myself: *Narcissus = undefined,
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echo: void = undefined,
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};
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pub fn main() void {
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print("Narcissus has room in his heart for:", .{});
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// Last time we examined the Narcissus struct, we had to
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// manually access each of the three fields. Our 'if'
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// statement was repeated three times almost verbatim. Yuck!
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//
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// Please use an 'inline for' to implement the block below
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// for each field in the slice 'fields'!
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const fields = @typeInfo(Narcissus).Struct.fields;
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inline for (fields) |field| {
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if (field.field_type != void) {
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print(" {s}", .{field.name});
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}
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}
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// Once you've got that, go back and take a look at exercise
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// 065 and compare what you've written to the abomination we
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// had there!
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print(".\n", .{});
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}
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