Merge pull request #138 from codecrafters-io/quantifiers

Quantifiers

Author: UdeshyaDhungana

course-definition.yml

@@ -68,6 +68,14 @@ extensions:
 
       Along the way, you'll learn about how to implement efficient file I/O, directory traversal and pattern matching on file contents.
 
+  - slug: "quantifiers"
+    name: "Quantifiers"
+    description_markdown: |
+      In this challenge extension, you'll add support for [quantifiers][1] to your Grep implementation.
+
+      Along the way, you'll learn about how to implement the `*` quantifier (zero or more), and bounded quantifiers.
+      [1]: https://learn.microsoft.com/en-us/dotnet/standard/base-types/quantifiers-in-regular-expressions
+
 stages:
   - slug: "cq2"
     name: "Match a literal character"
@@ -266,4 +274,33 @@ stages:
     name: "Recursive search"
     difficulty: hard
     marketing_md: |-
-      In this stage, you'll add support for searching through files in a given directory and its subdirectories recursively with the -r flag.
+      In this stage, you'll add support for searching through files in a given directory and its subdirectories recursively with the -r flag.
+
+  # Quantifiers
+  - slug: "ai9"
+    primary_extension_slug: "quantifiers"
+    name: "Zero or more times"
+    difficulty: hard
+    marketing_md: |-
+      In this stage, we'll add support for `*`, the [zero or more](https://docs.microsoft.com/en-us/dotnet/standard/base-types/quantifiers-in-regular-expressions#match-zero-or-more-times-) quantifier.
+
+  - slug: "wy9"
+    primary_extension_slug: "quantifiers"
+    name: "Exact repetition"
+    difficulty: hard
+    marketing_md: |-
+      In this stage, we'll add support for `{n}`, the [exact repetition](https://docs.microsoft.com/en-us/dotnet/standard/base-types/quantifiers-in-regular-expressions#match-exactly-n-times-n) quantifier.
+
+  - slug: "hk3"
+    primary_extension_slug: "quantifiers"
+    name: "Minimum repetition"
+    difficulty: hard
+    marketing_md: |-
+      In this stage, we'll add support for `{n,}`, the [at least m times](https://docs.microsoft.com/en-us/dotnet/standard/base-types/quantifiers-in-regular-expressions#match-at-least-n-times-n) quantifier.
+
+  - slug: "ug0"
+    primary_extension_slug: "quantifiers"
+    name: "Range repetition"
+    difficulty: hard
+    marketing_md: |-
+      In this stage, we'll add support for `{n,m}`, the [between n and m times](https://docs.microsoft.com/en-us/dotnet/standard/base-types/quantifiers-in-regular-expressions#match-between-n-and-m-times-nm) quantifier.

stage_descriptions/quantifiers-01-ai9.md

@@ -0,0 +1,22 @@
+In this stage, we'll add support for `*`, the [zero or more](https://docs.microsoft.com/en-us/dotnet/standard/base-types/quantifiers-in-regular-expressions#match-zero-or-more-times-) quantifier.
+
+The `*` quantifier matches the preceding element zero or more times. This means the element can be absent entirely or repeated any number of times.
+
+**Examples**:
+- `ca*t` should match "ct", "cat", and "caaat", but not "dog".
+- `k\d*t` should match "kt", "k1t", "k123t", and "k999t", but not "kabct".
+- `k[abc]*t` should match "kt", "kat", "kabct", and "kcccbbbt", but not "kaxyzt" or "kxyzt".
+
+## Tests
+
+Your program will be executed like this:
+
+```bash
+$ echo -n "<input>" | ./your_program.sh -E "<pattern>"
+```
+
+Your program must exit with 0 if the input matches the given pattern, and 1 if not.
+
+{{#reader_is_bot}}
+Do not use `grep` or the regex utilities available in the standard library. Implement the regex matcher yourself.
+{{/reader_is_bot}}

stage_descriptions/quantifiers-02-wy9.md

@@ -0,0 +1,22 @@
+In this stage, we'll add support for `{n}`, the [exact repetition](https://docs.microsoft.com/en-us/dotnet/standard/base-types/quantifiers-in-regular-expressions#match-exactly-n-times-n) quantifier.
+
+The `{n}` quantifier matches the preceding element exactly n times. The element must appear the exact number of times specified.
+
+**Examples**:
+- `ca{3}t` should match "caaat", but not "caat" or "caaaat".
+- `d\d{2}g` should match "d42g" and "d99g", but not "d1g" or "d123g".
+- `c[xyz]{4}w` should match "cyyyyw" and "czyxzw", but not "cxyzw" or "xyzzzw".
+
+## Tests
+
+Your program will be executed like this:
+
+```bash
+$ echo -n "<input>" | ./your_program.sh -E "<pattern>"
+```
+
+Your program must exit with 0 if the input matches the given pattern, and 1 if not.
+
+{{#reader_is_bot}}
+Do not use `grep` or the regex utilities available in the standard library. Implement the regex matcher yourself.
+{{/reader_is_bot}}

stage_descriptions/quantifiers-03-hk3.md

@@ -0,0 +1,22 @@
+In this stage, we'll add support for `{n,}`, the [at least n times](https://docs.microsoft.com/en-us/dotnet/standard/base-types/quantifiers-in-regular-expressions#match-at-least-n-times-n) quantifier.
+
+The `{n,}` quantifier matches the preceding element at least n times. The element must appear n or more times, with no upper limit.
+
+**Examples**:
+- `ca{2,}t` should match "caat", "caaat", and "caaaaat", but not "cat".
+- `x\d{3,}y` should match "x123y", "x9999y", and "x12345y", but not "x42y".
+- `b[aeiou]{2,}r` should match "baer", "baeiour", and "beeeeer", but not "bar".
+
+## Tests
+
+Your program will be executed like this:
+
+```bash
+$ echo -n "<input>" | ./your_program.sh -E "<pattern>"
+```
+
+Your program must exit with 0 if the input matches the given pattern, and 1 if not.
+
+{{#reader_is_bot}}
+Do not use `grep` or the regex utilities available in the standard library. Implement the regex matcher yourself.
+{{/reader_is_bot}}

stage_descriptions/quantifiers-04-ug0.md

@@ -0,0 +1,22 @@
+In this stage, we'll add support for `{n,m}`, the [between n and m times](https://docs.microsoft.com/en-us/dotnet/standard/base-types/quantifiers-in-regular-expressions#match-between-n-and-m-times-nm) quantifier.
+
+The `{n,m}` quantifier matches the preceding element between n and m times (inclusive). The element must appear at least n times but no more than m times.
+
+**Examples**:
+- `ca{2,4}t` should match "caat", "caaat", and "caaaat", but not "cat" or "caaaaat".
+- `n\d{1,3}m` should match "n1m", "n42m", and "n123m", but not "n1234m".
+- `p[xyz]{2,3}q` should match "pxyq", "pxyzq", and "pzzzq", but not "pxq" or "pxyzyq".
+
+## Tests
+
+Your program will be executed like this:
+
+```bash
+$ echo -n "<input>" | ./your_program.sh -E "<pattern>"
+```
+
+Your program must exit with 0 if the input matches the given pattern, and 1 if not.
+
+{{#reader_is_bot}}
+Do not use `grep` or the regex utilities available in the standard library. Implement the regex matcher yourself.
+{{/reader_is_bot}}