internal/span: handle character values beyond end of line in FromUTF16Column
On the assumption these implementations are designed to
support/implement the LSP spec, FromUTF16Column should handle the case
where a character value is beyond the end of the line.
https://github.com/Microsoft/language-server-protocol/blob/gh-pages/specification.md#position:
> * If the character value is greater than the line length it defaults back to the
> * line length.
Fixes golang/go#31883
Change-Id: I370845b7f2f046d8e84048a26bae5b23e9c27d06
Reviewed-on: https://go-review.googlesource.com/c/tools/+/185058
Run-TryBot: Paul Jolly <paul@myitcv.org.uk>
Reviewed-by: Ian Cottrell <iancottrell@google.com>
diff --git a/internal/span/utf16.go b/internal/span/utf16.go
index 5f90a51..55e6924 100644
--- a/internal/span/utf16.go
+++ b/internal/span/utf16.go
@@ -69,7 +69,11 @@
}
r, w := utf8.DecodeRune(remains)
if r == '\n' {
- return Point{}, fmt.Errorf("FromUTF16Column: chr goes beyond the line")
+ // Per the LSP spec:
+ //
+ // > If the character value is greater than the line length it
+ // > defaults back to the line length.
+ break
}
remains = remains[w:]
if r >= 0x10000 {
diff --git a/internal/span/utf16_test.go b/internal/span/utf16_test.go
index 2762772..0ae2749 100644
--- a/internal/span/utf16_test.go
+++ b/internal/span/utf16_test.go
@@ -185,12 +185,15 @@
post: "",
},
{
- scenario: "cursor beyond last character on line",
- input: funnyString,
- line: 1,
- offset: 0,
- utf16col: 6,
- err: "FromUTF16Column: chr goes beyond the line",
+ scenario: "cursor beyond last character on line",
+ input: funnyString,
+ line: 1,
+ offset: 0,
+ utf16col: 6,
+ resCol: 7,
+ resOffset: 6,
+ pre: "𐐀23",
+ post: "",
},
{
scenario: "cursor before funny character; second line",
