refactor: replace Split in loops with more efficient SplitSeq #1586
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Signed-off-by: findnature <[email protected]>
WalkthroughThe code modifies the method for splitting a string into lines by replacing the use of Changes
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Actionable comments posted: 1
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📒 Files selected for processing (1)
v2/pkg/testutils/integration.go(1 hunks)
🔇 Additional comments (1)
v2/pkg/testutils/integration.go (1)
30-30:✅ Verification successful
Verify SplitSeq is available in your Go version
The PR mentions replacing
SplitwithSplitSeqfor efficiency, butstrings.SplitSeqis not a standard function in the Go standard library as of my knowledge. Please ensure this function exists in your environment or that you're using a custom package that provides it.
🏁 Script executed:
#!/bin/bash # Check if SplitSeq exists in the Go strings package go doc strings.SplitSeq echo "Exit code: $?" # Check Go version go version # Look for any imports that might provide SplitSeq grep -r "SplitSeq" --include="*.go" .Length of output: 540
No action needed: strings.SplitSeq is available in Go 1.24
- Verified with
go version go1.24.1 linux/amd64.go doc strings.SplitSeqshows it returningiter.Seq[string]in the standard library.
| items := strings.SplitSeq(string(data), "\n") | ||
| for i := range items { | ||
| if i != "" { | ||
| parts = append(parts, i) | ||
| } |
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Critical issue: Incorrect loop variable usage
The refactoring from strings.Split to strings.SplitSeq is a good optimization, but there are two critical issues in the implementation:
- When using
for i := range items, the variableirepresents the index, not the value at that index. - The condition
if i != ""is incorrectly comparing an integer index with an empty string, which will cause a compilation error. - Line 33 attempts to append an integer index to a string slice, which will also fail.
Here's how to fix it:
items := strings.SplitSeq(string(data), "\n")
- for i := range items {
- if i != "" {
- parts = append(parts, i)
+ for i := range items {
+ if items[i] != "" {
+ parts = append(parts, items[i])
}
}Alternatively, you could use the original value-based loop approach:
items := strings.SplitSeq(string(data), "\n")
- for i := range items {
- if i != "" {
+ for _, item := range items {
+ if item != "" {
- parts = append(parts, i)
+ parts = append(parts, item)
}
}📝 Committable suggestion
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| items := strings.SplitSeq(string(data), "\n") | |
| for i := range items { | |
| if i != "" { | |
| parts = append(parts, i) | |
| } | |
| items := strings.SplitSeq(string(data), "\n") | |
| for _, item := range items { | |
| if item != "" { | |
| parts = append(parts, item) | |
| } | |
| } |
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the function description:
"SplitSeq returns an iterator over all substrings of s separated by sep. The iterator yields the same strings that would be returned by [Split](s, sep), but without constructing the slice. It returns a single-use iterator."
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🧩 Analysis chain
Let me check the Go documentation and explore how SplitSeq should be properly used, as it seems to be different from Split.
@dogancanbakir Thank you for sharing the function description. Based on this, I see the issue with the current implementation. Since SplitSeq returns an iterator rather than a slice, we need to use it differently.
Here's the correct way to use SplitSeq:
var parts []string
iter := strings.SplitSeq(string(data), "\n")
for iter.Next() {
item := iter.Value()
if item != "" {
parts = append(parts, item)
}
}The current PR implementation is incorrect because it's treating the iterator as a slice. With SplitSeq, you need to use the Next() and Value() methods to properly iterate through the results rather than using a range loop.
🏁 Script executed:
#!/bin/bash
# Check Go documentation for SplitSeq
go doc strings.SplitSeq || echo "Documentation not found"
# Look for examples of SplitSeq usage in the codebase
rg "SplitSeq" -A 3 -B 3
# Check the Go stdlib strings package
curl -s https://pkg.go.dev/strings | grep -A 10 "SplitSeq"
Length of output: 3169
@dogancanbakir Thanks for providing that function description. Looking at the Go documentation, SplitSeq returns an iter.Seq[string] object, which is an iterator, not a slice like Split returns.
The current implementation is incorrect because it's trying to range over an iterator and directly use the index variable as a string. Here's the correct way to use SplitSeq:
var parts []string
iter := strings.SplitSeq(string(data), "\n")
for iter.Next() {
item := iter.Value()
if item != "" {
parts = append(parts, item)
}
}Since SplitSeq returns a single-use iterator, you need to use the Next() method to advance through the items and Value() to retrieve each string, rather than using a range loop like you would with a slice.
✏️ Learnings added
Learnt from: dogancanbakir
PR: projectdiscovery/subfinder#1586
File: v2/pkg/testutils/integration.go:30-34
Timestamp: 2025-05-17T13:17:03.433Z
Learning: In Go, `strings.SplitSeq` returns an iterator that must be used with the `Next()` and `Value()` methods, unlike `strings.Split` which returns a slice. When replacing `Split` with `SplitSeq` for performance optimization, the iteration pattern must be changed accordingly.
Learnt from: dogancanbakir
PR: projectdiscovery/subfinder#1586
File: v2/pkg/testutils/integration.go:30-34
Timestamp: 2025-05-17T13:17:03.433Z
Learning: In Go, when replacing `strings.Split` with `strings.SplitSeq` (added in Go 1.24.0), the implementation must change from using range loops on slices to using the iterator pattern with `Next()` and `Value()` methods, as `SplitSeq` returns an `iter.Seq[string]` iterator rather than a string slice.
Note: Learnings are effective only in the context of similar code segments. To apply general coding guidelines, please configure review instructions. You can manage existing learnings in the app.
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Thanks! |
|
Anything need I to do? |
| @@ -27,8 +27,8 @@ func RunSubfinderAndGetResults(debug bool, domain string, extra ...string) ([]st | |||
| return nil, err | |||
| } | |||
| var parts []string | |||
| items := strings.Split(string(data), "\n") | |||
| for _, i := range items { | |||
| items := strings.SplitSeq(string(data), "\n") | |||
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Can we update other instances as well?
Optimize code using a more modern writing style. Official support from Go, for more details visit https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/modernize.
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