diff options
author | Joe Tsai <joetsai@digital-static.net> | 2020-06-17 17:25:47 -0700 |
---|---|---|
committer | GitHub <noreply@github.com> | 2020-06-17 17:25:47 -0700 |
commit | 77ae86f624cb174e21763cffcbbf070eb06cb016 (patch) | |
tree | dd32bd59eb58b50d44dee2efa06ac36f8daa92a1 /cmp/report_text.go | |
parent | c49bfce0ac9115b09320b47c3b9534cc5afd4579 (diff) | |
download | go-cmp-77ae86f624cb174e21763cffcbbf070eb06cb016.tar.gz |
Improve reporting of values with cycles (#217)
Previously, the reporter could handle formatting values with cycles
in that it did not crash with a stack overflow. However, the output
was not particularly understandable as it did not surface to the user
why a particular value was truncated, and if it was truncated due
to a cyclic reference, what was the referent.
This change annotates the reporter tree with pointer information
so that a later pass can inject reference information if it is needed
to produce more understandable output.
Consider the following example:
map[string]*cmp_test.CycleAlpha{
"Foo": &⟪ref#0⟫{
Name: "Foo",
Bravos: map[string]*cmp_test.CycleBravo{
"FooBravo": &{
- ID: 101,
+ ID: 0,
Name: "FooBravo",
Mods: 100,
Alphas: {"Foo": &⟪ref#0⟫(...)},
},
},
},
}
This graph contains a cycle. To ensure that a graph can be formatted,
the cycle is truncated as indicated with: &⟪ref#0⟫(...).
The referent was identified earlier with: &⟪ref#0⟫{...}.
Diffstat (limited to 'cmp/report_text.go')
-rw-r--r-- | cmp/report_text.go | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/cmp/report_text.go b/cmp/report_text.go index b8ec9d2..8b12c05 100644 --- a/cmp/report_text.go +++ b/cmp/report_text.go @@ -94,21 +94,22 @@ type textNode interface { // textWrap is a wrapper that concatenates a prefix and/or a suffix // to the underlying node. type textWrap struct { - Prefix string // e.g., "bytes.Buffer{" - Value textNode // textWrap | textList | textLine - Suffix string // e.g., "}" + Prefix string // e.g., "bytes.Buffer{" + Value textNode // textWrap | textList | textLine + Suffix string // e.g., "}" + Metadata interface{} // arbitrary metadata; has no effect on formatting } -func (s textWrap) Len() int { +func (s *textWrap) Len() int { return len(s.Prefix) + s.Value.Len() + len(s.Suffix) } -func (s1 textWrap) Equal(s2 textNode) bool { - if s2, ok := s2.(textWrap); ok { +func (s1 *textWrap) Equal(s2 textNode) bool { + if s2, ok := s2.(*textWrap); ok { return s1.Prefix == s2.Prefix && s1.Value.Equal(s2.Value) && s1.Suffix == s2.Suffix } return false } -func (s textWrap) String() string { +func (s *textWrap) String() string { var d diffMode var n indentMode _, s2 := s.formatCompactTo(nil, d) @@ -117,7 +118,7 @@ func (s textWrap) String() string { b = append(b, '\n') // Trailing newline return string(b) } -func (s textWrap) formatCompactTo(b []byte, d diffMode) ([]byte, textNode) { +func (s *textWrap) formatCompactTo(b []byte, d diffMode) ([]byte, textNode) { n0 := len(b) // Original buffer length b = append(b, s.Prefix...) b, s.Value = s.Value.formatCompactTo(b, d) @@ -127,7 +128,7 @@ func (s textWrap) formatCompactTo(b []byte, d diffMode) ([]byte, textNode) { } return b, s } -func (s textWrap) formatExpandedTo(b []byte, d diffMode, n indentMode) []byte { +func (s *textWrap) formatExpandedTo(b []byte, d diffMode, n indentMode) []byte { b = append(b, s.Prefix...) b = s.Value.formatExpandedTo(b, d, n) b = append(b, s.Suffix...) @@ -195,7 +196,7 @@ func (s1 textList) Equal(s2 textNode) bool { } func (s textList) String() string { - return textWrap{"{", s, "}"}.String() + return (&textWrap{Prefix: "{", Value: s, Suffix: "}"}).String() } func (s textList) formatCompactTo(b []byte, d diffMode) ([]byte, textNode) { |