[Concept] String Functions - add exercise templates #158
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WalkthroughThis PR adds a new "String Functions" exercise (47_string_functions) to the Go learning curriculum. Changes include updating documentation, adding catalog entries, creating template stubs with tests, and providing complete solutions that wrap standard library string utilities. Changes
Estimated code review effort🎯 2 (Simple) | ⏱️ ~10 minutes
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🔇 Additional comments (5)
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📒 Files selected for processing (8)
docs/exercises.md(1 hunks)internal/exercises/catalog.yaml(3 hunks)internal/exercises/solutions/41_regex/regex.go(1 hunks)internal/exercises/solutions/42_string_functions/string_functions.go(1 hunks)internal/exercises/templates/41_regex/regex.go(1 hunks)internal/exercises/templates/41_regex/regex_test.go(1 hunks)internal/exercises/templates/42_string_functions/string_functions.go(1 hunks)internal/exercises/templates/42_string_functions/string_functions_test.go(1 hunks)
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🧬 Code graph analysis (3)
internal/exercises/templates/42_string_functions/string_functions_test.go (1)
internal/exercises/templates/42_string_functions/string_functions.go (7)
Contains(7-10)HasPrefix(13-16)HasSuffix(19-22)Index(25-28)ToUpper(31-34)ToLower(37-40)TrimSpace(43-46)
internal/exercises/templates/42_string_functions/string_functions.go (1)
internal/exercises/solutions/42_string_functions/string_functions.go (7)
Contains(6-8)HasPrefix(11-13)HasSuffix(16-18)Index(21-23)ToUpper(26-28)ToLower(31-33)TrimSpace(36-38)
internal/exercises/solutions/42_string_functions/string_functions.go (1)
internal/exercises/templates/42_string_functions/string_functions.go (7)
Contains(7-10)HasPrefix(13-16)HasSuffix(19-22)Index(25-28)ToUpper(31-34)ToLower(37-40)TrimSpace(43-46)
🔇 Additional comments (25)
internal/exercises/templates/42_string_functions/string_functions_test.go (7)
5-25: LGTM! Comprehensive test coverage for Contains.The test cases cover typical scenarios, edge cases (empty strings), and negative cases effectively. The table-driven approach is idiomatic Go.
27-46: LGTM! Good test coverage for HasPrefix.The test cases appropriately validate prefix matching behavior including edge cases.
48-67: LGTM! Good test coverage for HasSuffix.The test cases appropriately validate suffix matching behavior including edge cases.
69-89: LGTM! Good test coverage for Index.The test cases correctly validate index finding behavior, including the -1 return for not found and first occurrence behavior.
91-110: LGTM! Excellent Unicode coverage.The test cases include proper Unicode handling with accented characters, which is important for internationalization. Good comprehensive coverage.
112-131: LGTM! Excellent Unicode coverage.The test cases include proper Unicode handling with accented characters, mirroring the ToUpper tests appropriately.
133-153: LGTM! Comprehensive whitespace handling.The test cases cover various types of whitespace (spaces, tabs, newlines) and edge cases effectively.
internal/exercises/solutions/42_string_functions/string_functions.go (7)
5-8: LGTM! Clean wrapper implementation.The function correctly delegates to the standard library
strings.Contains.
10-13: LGTM! Clean wrapper implementation.The function correctly delegates to the standard library
strings.HasPrefix.
15-18: LGTM! Clean wrapper implementation.The function correctly delegates to the standard library
strings.HasSuffix.
20-23: LGTM! Clean wrapper implementation.The function correctly delegates to the standard library
strings.Index.
25-28: LGTM! Clean wrapper implementation.The function correctly delegates to the standard library
strings.ToUpper.
30-33: LGTM! Clean wrapper implementation.The function correctly delegates to the standard library
strings.ToLower.
35-38: LGTM! Clean wrapper implementation.The function correctly delegates to the standard library
strings.TrimSpace.internal/exercises/templates/42_string_functions/string_functions.go (1)
1-46: LGTM! Well-structured exercise template.The template correctly provides function skeletons with:
- Clear TODO comments indicating which standard library function to use
- Intentionally incorrect return values that will fail tests
- Proper function signatures matching the solution
- Helpful reminder to import the strings package
This structure will effectively guide learners through the exercise.
internal/exercises/templates/41_regex/regex_test.go (4)
5-25: LGTM! Comprehensive email validation test cases.The test cases cover valid emails and common invalid patterns (missing @, missing domain, missing TLD, empty string).
27-52: LGTM! Good coverage for number extraction.The test cases appropriately handle integers, decimals, and edge cases like "12.34.56" being parsed as two separate numbers.
54-74: LGTM! Thorough vowel replacement tests.The test cases cover case-insensitive replacement, strings with no vowels, and strings composed entirely of vowels.
76-99: LGTM! Comprehensive phone number validation tests.The test cases thoroughly validate the specific format (XXX) XXX-XXXX, testing various invalid formats including missing punctuation, wrong spacing, and incorrect digit counts.
internal/exercises/catalog.yaml (5)
177-184: LGTM! JSON exercise added to concepts.The JSON exercise is properly configured with appropriate hints for marshaling/unmarshaling and error handling.
193-219: LGTM! Additional exercises added to concepts.Exercises 37 (Sorting by Functions), 38 (Time Formatting), and 39 (Channel Directions) are properly configured with helpful hints.
226-238: LGTM! Regex exercise properly configured.The regex exercise has comprehensive hints covering all four functions with specific regex patterns provided. This will be helpful for learners.
239-246: LGTM! String Functions exercise properly configured.The string functions exercise has clear hints for all seven functions, properly guiding learners to the appropriate strings package functions.
247-295: LGTM! Projects section appropriately reorganized.The removal of concept exercises (36-39) from the projects section aligns with their addition to the concepts section, creating better organizational structure.
internal/exercises/templates/41_regex/regex.go (1)
1-37: LGTM! Well-structured regex exercise template.The template provides:
- Clear task description with numbered objectives
- Function skeletons with appropriate TODOs
- Intentionally incorrect return values that will fail tests
- Helpful comments indicating which regexp functions to use
This structure effectively guides learners through implementing regex functionality.
docs/exercises.md
Outdated
| <li>41_regex - Regular Expressions</li> | ||
| <li>42_string_functions - String Functions</li> | ||
| <li>36_json - JSON Processing</li> |
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🛠️ Refactor suggestion | 🟠 Major
🧩 Analysis chain
Verify exercise numbering sequence.
The new exercises 41_regex and 42_string_functions are listed before 36_json in the Advanced section. This breaks the numerical sequence. Consider either:
- Reordering to maintain numerical sequence (36, 37, 41, 42)
- Or renumbering these exercises to fit sequentially
However, if exercises 38-40 exist elsewhere and this ordering is intentional, this is acceptable.
Run this script to check if exercises 38, 39, and 40 exist in the catalog:
🏁 Script executed:
#!/bin/bash
# Check for exercises 38, 39, and 40 in the catalog
grep -E "slug: (38|39|40)_" internal/exercises/catalog.yamlLength of output: 82
🏁 Script executed:
#!/bin/bash
# Check where exercises 38, 39, 40 appear in docs/exercises.md
grep -n "38_\|39_\|40_" docs/exercises.mdLength of output: 0
🏁 Script executed:
#!/bin/bash
# Show the full structure around lines 52-54 with context
sed -n '40,60p' docs/exercises.mdLength of output: 622
Reorder Advanced exercises in docs/exercises.md
- In the Advanced (21-37) section, move
<li>36_json – JSON Processing</li>and<li>37_xml – XML Processing</li>above the new entries (<li>41_regex – Regular Expressions</li>,<li>42_string_functions – String Functions</li>). - Update the section header to
Advanced (21-42)if you intend to include 41 and 42 here.
🤖 Prompt for AI Agents
In docs/exercises.md around lines 52 to 54, the Advanced section items are out
of order and the header range is inconsistent: move the two existing items
<li>36_json – JSON Processing</li> and <li>37_xml – XML Processing</li> so they
appear above the new entries <li>41_regex – Regular Expressions</li> and
<li>42_string_functions – String Functions</li>, and update the Advanced section
header to read "Advanced (21-42)" to reflect inclusion of exercises 41 and 42.
| package regex | ||
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| // Task: | ||
| // Implement regular expression functions using Go's regexp package. | ||
| // | ||
| // 1. Implement IsValidEmail to validate email addresses using regex. | ||
| // 2. Implement ExtractNumbers to extract all numbers from a string. | ||
| // 3. Implement ReplaceVowels to replace all vowels with asterisks. | ||
| // 4. Implement IsPhoneNumber to validate phone numbers in format (XXX) XXX-XXXX. | ||
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| // IsValidEmail should return true if the email address is valid. | ||
| // A valid email should have the format: [email protected] | ||
| func IsValidEmail(email string) bool { | ||
| // TODO: implement using regexp.MustCompile and MatchString | ||
| return false | ||
| } | ||
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| // ExtractNumbers should return all numbers found in the input string. | ||
| // Numbers can be integers or decimals (e.g., "123", "45.67"). | ||
| func ExtractNumbers(text string) []string { | ||
| // TODO: implement using regexp.FindAllString | ||
| return nil | ||
| } | ||
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| // ReplaceVowels should replace all vowels (a, e, i, o, u) with asterisks. | ||
| // Case-insensitive replacement. | ||
| func ReplaceVowels(text string) string { | ||
| // TODO: implement using regexp.MustCompile and ReplaceAllString | ||
| return "" | ||
| } | ||
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| // IsPhoneNumber should return true if the phone number matches format (XXX) XXX-XXXX. | ||
| // Example: (123) 456-7890 | ||
| func IsPhoneNumber(phone string) bool { | ||
| // TODO: implement using regexp.MustCompile and MatchString | ||
| return false | ||
| } |
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🧩 Analysis chain
Solution file contains only placeholder implementations.
This file is located in the solutions/ directory but contains only TODO comments and placeholder return values. Solution files should provide working reference implementations that pass all tests, unlike template files which intentionally fail.
Verify whether this is intentional or if the actual regex implementations need to be added.
I'll verify the repository structure and conventions around solution files to determine if this is a legitimate concern.
🏁 Script executed:
#!/bin/bash
# Check if the file exists and examine surrounding structure
echo "=== File existence and location ==="
find . -type f -name "regex.go" | head -20
echo -e "\n=== Directory structure around solutions/41_regex/ ==="
fd -t d "41_regex|regex" | head -20
echo -e "\n=== Check for template vs solutions structure ==="
find . -type d \( -name "solutions" -o -name "template" -o -name "templates" \) | head -10
echo -e "\n=== List solution files to understand pattern ==="
find . -path "*/solutions/*" -name "*.go" -type f | head -15Length of output: 1280
🏁 Script executed:
#!/bin/bash
# Examine content of a few solution files to see if they have implementations or just placeholders
echo "=== Sample solution files content ==="
for file in $(find . -path "*/solutions/*" -name "*.go" -type f | head -5); do
echo "File: $file"
echo "First 30 lines:"
head -30 "$file"
echo -e "\n---\n"
doneLength of output: 1896
🏁 Script executed:
#!/bin/bash
# Check for documentation about the exercise structure
echo "=== Looking for README or documentation ==="
find . -iname "readme*" -o -iname "*.md" | grep -E "(exercise|solution|regex)" | head -10
echo -e "\n=== General README files ==="
find . -maxdepth 3 -iname "readme*" -type fLength of output: 105
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#!/bin/bash
# Compare the template and solution regex.go files
echo "=== SOLUTIONS FILE: solutions/41_regex/regex.go ==="
cat ./internal/exercises/solutions/41_regex/regex.go
echo -e "\n=== TEMPLATES FILE: templates/41_regex/regex.go ==="
cat ./internal/exercises/templates/41_regex/regex.goLength of output: 2756
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#!/bin/bash
# Check documentation to understand the intent
echo "=== EXERCISES DOCUMENTATION ==="
cat ./docs/exercises.mdLength of output: 2798
Populate regex solution file with real implementations
The file internal/exercises/solutions/41_regex/regex.go is identical to its template and only contains TODO placeholders. Unlike other solution files, it needs working implementations of IsValidEmail, ExtractNumbers, ReplaceVowels, and IsPhoneNumber using Go’s regexp package so that all tests pass.
🤖 Prompt for AI Agents
In internal/exercises/solutions/41_regex/regex.go around lines 1-37 the four
functions are unimplemented; implement them using Go's regexp package:
IsValidEmail should compile a basic anchored email pattern (e.g.
`^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}$`) and return
regexp.MustCompile(...).MatchString(email); ExtractNumbers should use a regex
like `\d+(?:\.\d+)?` and return re.FindAllString(text, -1); ReplaceVowels should
use a case-insensitive vowel regex `(?i)[aeiou]` and return
re.ReplaceAllString(text, "*"); IsPhoneNumber should use an anchored pattern for
`(XXX) XXX-XXXX` like `^\(\d{3}\) \d{3}-\d{4}$` and return MatchString(phone).
Ensure proper return types and no panics by using regexp.MustCompile as
requested.
|
@aryasoni98 Please limit the PR scope to a single exercise. |
…ctions (zhravan#77) - Removed all 41_regex exercise files (templates and solutions) - Removed 41_regex entry from catalog.yaml - Updated docs/exercises.md: - Removed regex reference - Reordered exercises (36_json, 37_xml before 44_string_functions) - Updated section header to 'Advanced (21-44)' - PR now focuses solely on String Functions exercise as requested
- Integrated new exercises from main: 44_atomic_counters, 45_range_over_channels, 46_non_blocking_channel_operations - Renumbered string_functions from 44 to 47 to avoid conflicts - Updated catalog.yaml with all exercises in proper order - Updated docs/exercises.md section header to Advanced (21-47)
2 participants
Summary
Added String Functions exercise (#42) to teach Go's strings package fundamentals
This change implements issue #77 by adding a comprehensive String Functions exercise that teaches students essential string manipulation functions from Go's standard library. The exercise covers 7 key functions:
Contains,HasPrefix,HasSuffix,Index,ToUpper,ToLower, andTrimSpace.Motivation: Students need to understand Go's built-in string functions for effective string manipulation. This exercise fills a gap in the curriculum by providing hands-on practice with the most commonly used strings package functions.
Checklist
docs/exercises.mdin the Advanced sectionstringspackageScreenshots / Output (if CLI UX)
Template Test Output (Expected Failures):
Solution Test Output (All Pass):
Related issues
Fixes #77
Summary by CodeRabbit
New Exercises
Exercise Catalog Updates
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