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March 03, 2019 Help with Regular Expressions (std.regex) | ||||
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I am belatedly working my way through the 2018 edition of the Advent of Code[1] programming challenges using D and am stumped on Problem 3[2]. The challenge requires you to parse a set of lines in the format: #99 @ 652,39: 24x23 #100 @ 61,13: 15x24 #101 @ 31,646: 16x28 I would like to store each number (match) as an element in an array so that I can refer to them by index. For example, for the first line: m = [99, 652, 39, 24, 23] assert(m[0] == 99); assert(m[1] == 652); // ... assert(m[4] == 23); What is the best way to do this? (I will worry about converting characters to integers later.) I have the following solution so far based on reading Dmitry Olshansky's article on std.regex[3] and the std.regex documention[4]: import std.stdio; import std.regex; void main() { auto line = "#99 @ 652,39: 24x23"; auto pattern = regex(r"\d+"); auto m = matchAll(line, pattern); writeln(m); } which results in: [["99"], ["652"], ["39"], ["24"], ["23"]] But this doesn't seem to be an iterable array as changing writeln(m) to writeln(m[0]) yields Error: no [] operator overload for type RegexMatch!string Changing the line to writeln(m.front[0]) yields 99 but m.front doesn't allow me to access other elements (i.e. m.front[1]): requested submatch number 1 is out of range ---------------- ??:? _d_assert_msg [0x4dc27a] ??:? inout pure nothrow @trusted inout(immutable(char)[]) std.regex.Captures!(immutable(char)[]).Captures.opIndex!().opIndex(ulong) [0x4d8d57] ??:? _Dmain [0x49ffc8] I've tried something like foreach (m; matchAll(line, pattern)) writeln(m.hit); which is close but doesn't result in an array. Do I need to use matchFirst? Thanks in advance. Samir [1] https://adventofcode.com/2018 [2] https://adventofcode.com/2018/day/3 [3] https://dlang.org/articles/regular-expression.html [4] https://dlang.org/phobos/std_regex.html |
March 03, 2019 Re: Help with Regular Expressions (std.regex) | ||||
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Posted in reply to Samir | On Sunday, 3 March 2019 at 18:07:57 UTC, Samir wrote:
> I am belatedly working my way through the 2018 edition of the Advent of Code[1] programming challenges using D and am stumped on Problem 3[2]. The challenge requires you to parse a set of lines in the format:
> #99 @ 652,39: 24x23
> #100 @ 61,13: 15x24
> #101 @ 31,646: 16x28
>
> I would like to store each number (match) as an element in an array so that I can refer to them by index. For example, for the first line:
>
> m = [99, 652, 39, 24, 23]
> assert(m[0] == 99);
> assert(m[1] == 652);
> // ...
> assert(m[4] == 23);
>
> What is the best way to do this? (I will worry about converting characters to integers later.)
>
> I have the following solution so far based on reading Dmitry Olshansky's article on std.regex[3] and the std.regex documention[4]:
>
> import std.stdio;
> import std.regex;
>
> void main() {
> auto line = "#99 @ 652,39: 24x23";
> auto pattern = regex(r"\d+");
> auto m = matchAll(line, pattern);
> writeln(m);
> }
>
> which results in:
> [["99"], ["652"], ["39"], ["24"], ["23"]]
>
> But this doesn't seem to be an iterable array as changing writeln(m) to writeln(m[0]) yields
> Error: no [] operator overload for type RegexMatch!string
>
> Changing the line to writeln(m.front[0]) yields
> 99
>
> but m.front doesn't allow me to access other elements (i.e. m.front[1]):
> requested submatch number 1 is out of range
> ----------------
> ??:? _d_assert_msg [0x4dc27a]
> ??:? inout pure nothrow @trusted inout(immutable(char)[]) std.regex.Captures!(immutable(char)[]).Captures.opIndex!().opIndex(ulong) [0x4d8d57]
> ??:? _Dmain [0x49ffc8]
>
> I've tried something like
> foreach (m; matchAll(line, pattern))
> writeln(m.hit);
>
> which is close but doesn't result in an array. Do I need to use matchFirst?
>
> Thanks in advance.
> Samir
>
> [1] https://adventofcode.com/2018
> [2] https://adventofcode.com/2018/day/3
> [3] https://dlang.org/articles/regular-expression.html
> [4] https://dlang.org/phobos/std_regex.html
Hello, Something like this should work:
import std.array: array;
auto allMatches = matchAll(line, pattern).array;
or // sorry i don't have the regex API in mind
import std.array: array;
import std.alogrithm.iteration : map;
auto allMatches = matchAll(line, pattern).map(a => a.hit).array;
What happened with `writeln` is that it iterates the `matchAll` results which is an input range, which is lazy. `.array` stores the results in an array.
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March 03, 2019 Re: Help with Regular Expressions (std.regex) | ||||
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Posted in reply to user1234 | On Sunday, 3 March 2019 at 18:32:14 UTC, user1234 wrote:
> On Sunday, 3 March 2019 at 18:07:57 UTC, Samir wrote:
> or // sorry i don't have the regex API in mind
>
> import std.array: array;
> import std.alogrithm.iteration : map;
> auto allMatches = matchAll(line, pattern).map(a => a.hit).array;
oops forgot the bang
auto allMatches = matchAll(line, pattern).map!(a => a.hit).array;
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March 04, 2019 Re: Help with Regular Expressions (std.regex) | ||||
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Posted in reply to user1234 | On Sunday, 3 March 2019 at 19:27:17 UTC, user1234 wrote:
> oops forgot the bang
>
> auto allMatches = matchAll(line, pattern).map!(a => a.hit).array;
Thanks, user1234! Looks like `map` is another topic I need to read up upon. I slightly modified your suggestion and went with:
auto allMatches = matchAll(line, pattern).map!(a => to!int(a.hit)).array;
which also takes care of converting the string to int.
Samir
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March 04, 2019 Re: Help with Regular Expressions (std.regex) | ||||
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Posted in reply to Samir | On 3/3/19 7:07 PM, Samir via Digitalmars-d-learn wrote:
> I am belatedly working my way through the 2018 edition of the Advent of Code[1] programming challenges using D and am stumped on Problem 3[2]. The challenge requires you to parse a set of lines in the format:
> #99 @ 652,39: 24x23
> #100 @ 61,13: 15x24
> #101 @ 31,646: 16x28
>
> I would like to store each number (match) as an element in an array so that I can refer to them by index.
There is also std.file.slurp which makes this quite easy:
slurp!(int, int, int, int, int)("03.input", "#%d @ %d,%d: %dx%d");
You can then later expand the matches in a loop and process the claims:
foreach(id, offX, offY, width, height; ...
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March 05, 2019 Re: Help with Regular Expressions (std.regex) | ||||
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Posted in reply to dwdv | On Monday, 4 March 2019 at 18:57:34 UTC, dwdv wrote:
> There is also std.file.slurp which makes this quite easy:
> slurp!(int, int, int, int, int)("03.input", "#%d @ %d,%d: %dx%d");
That's brilliant! This language just keeps putting a smile on my face every time I learn something new like this!
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