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Add str/prn for Diff, refactor unified, add unified-with-context #9

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Merged
hellerve merged 1 commit into from
Jun 22, 2026
Merged

Add str/prn for Diff, refactor unified, add unified-with-context #9

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195 changes: 103 additions & 92 deletions diff.carp
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,20 @@
(Deletion x) (match @b (Deletion y) (= &x &y) _ false)))
(implements = Diff.=)

(defn str [d]
(match-ref d
(Eq x) (String.concat &[@"(Eq " (str x) @")"])
(Insertion x) (String.concat &[@"(Insertion " (str x) @")"])
(Deletion x) (String.concat &[@"(Deletion " (str x) @")"])))
(implements str Diff.str)

(defn prn [d]
(match-ref d
(Eq x) (String.concat &[@"(Eq " (prn x) @")"])
(Insertion x) (String.concat &[@"(Insertion " (prn x) @")"])
(Deletion x) (String.concat &[@"(Deletion " (prn x) @")"])))
(implements prn Diff.prn)

(doc diff
"Computes the diff between two arrays, returning a sequence of Eq, Insertion, and Deletion hunks.")
(defn diff [old new]
Expand Down Expand Up @@ -125,7 +139,9 @@
1.0
(/ (Double.from-int (* 2 (lcs-length old new))) (Double.from-int total)))))

(defn- emit-hunk [output old-start old-count new-start new-count hunk-lines]
(defn- change? [d] (match-ref d (Eq _) false _ true))

(defn- format-hunk [old-start old-count new-start new-count hunk-lines]
(let [header (String.concat
&[@"@@ -"
(Int.str old-start)
Expand All @@ -138,16 +154,16 @@
@" @@"])
body (String.join "
" hunk-lines)]
(String.concat &[output header @"
(String.concat &[header @"
" body @"
"])))

(doc unified "Renders a line diff in unified diff format with hunk headers.
(doc unified-with-context
"Renders a line diff in unified diff format with hunk headers.
Expects the output of `line-diff` or a diff of string arrays.
Uses 3 lines of context around changes.")
(defn unified [d]
(let-do [ctx 3
old-pos 1
Uses the given number of context lines around changes.")
(defn unified-with-context [d ctx]
(let-do [old-pos 1
new-pos 1
hunk-lines (the (Array String) [])
hunk-old-start 1
Expand All @@ -159,97 +175,92 @@ Uses 3 lines of context around changes.")
lead-old-start 1
lead-new-start 1
lead-count 0
result @""]
hunks (the (Array String) [])]
(for [i 0 (Array.length d)]
(match-ref (Array.unsafe-nth d i)
(Eq lines)
(let-do [n (Array.length lines)]
(if in-hunk
(if (<= n (* 2 ctx))
(for [j 0 n]
(let-do [line (Array.unsafe-nth lines j)]
(Array.push-back! &hunk-lines
(String.concat &[@" " @line]))
(set! hunk-old-count (+ hunk-old-count 1))
(set! hunk-new-count (+ hunk-new-count 1))))
(let-do [trailing (Int.min ctx n)]
(for [j 0 trailing]
(let-do [elem (Array.unsafe-nth d i)]
(when-do (and (not in-hunk) (change? elem))
(set! in-hunk true)
(set! hunk-lines (Array.copy &lead-lines))
(set! hunk-old-start lead-old-start)
(set! hunk-new-start lead-new-start)
(set! hunk-old-count lead-count)
(set! hunk-new-count lead-count)
(set! lead-lines [])
(set! lead-count 0))
(match-ref elem
(Eq lines)
(let-do [n (Array.length lines)]
(if in-hunk
(if (<= n (* 2 ctx))
(for [j 0 n]
(let-do [line (Array.unsafe-nth lines j)]
(Array.push-back! &hunk-lines
(String.concat &[@" " @line]))
(set! hunk-old-count (+ hunk-old-count 1))
(set! hunk-new-count (+ hunk-new-count 1))))
(set! result
(emit-hunk result
hunk-old-start
hunk-old-count
hunk-new-start
hunk-new-count
&hunk-lines))
(set! in-hunk false)
(set! hunk-lines [])
(let-do [leading (Int.min ctx (- n trailing))
lead-start (- n leading)]
(set! lead-lines [])
(set! lead-count 0)
(set! lead-old-start (+ old-pos lead-start))
(set! lead-new-start (+ new-pos lead-start))
(for [j lead-start n]
(let-do [trailing (Int.min ctx n)]
(for [j 0 trailing]
(let-do [line (Array.unsafe-nth lines j)]
(Array.push-back! &lead-lines
(Array.push-back! &hunk-lines
(String.concat &[@" " @line]))
(set! lead-count (+ lead-count 1)))))))
(let-do [leading (Int.min ctx n)
lead-start (- n leading)]
(set! lead-lines [])
(set! lead-count 0)
(set! lead-old-start (+ old-pos lead-start))
(set! lead-new-start (+ new-pos lead-start))
(for [j lead-start n]
(let-do [line (Array.unsafe-nth lines j)]
(Array.push-back! &lead-lines
(String.concat &[@" " @line]))
(set! lead-count (+ lead-count 1))))))
(set! old-pos (+ old-pos n))
(set! new-pos (+ new-pos n)))
(Deletion lines)
(let-do [n (Array.length lines)]
(unless-do in-hunk
(set! in-hunk true)
(set! hunk-lines (Array.copy &lead-lines))
(set! hunk-old-start lead-old-start)
(set! hunk-new-start lead-new-start)
(set! hunk-old-count lead-count)
(set! hunk-new-count lead-count)
(set! lead-lines [])
(set! lead-count 0))
(for [j 0 n]
(let-do [line (Array.unsafe-nth lines j)]
(Array.push-back! &hunk-lines (String.concat &[@"-" @line]))
(set! hunk-old-count (+ hunk-old-count 1))))
(set! old-pos (+ old-pos n)))
(Insertion lines)
(let-do [n (Array.length lines)]
(unless-do in-hunk
(set! in-hunk true)
(set! hunk-lines (Array.copy &lead-lines))
(set! hunk-old-start lead-old-start)
(set! hunk-new-start lead-new-start)
(set! hunk-old-count lead-count)
(set! hunk-new-count lead-count)
(set! lead-lines [])
(set! lead-count 0))
(for [j 0 n]
(let-do [line (Array.unsafe-nth lines j)]
(Array.push-back! &hunk-lines (String.concat &[@"+" @line]))
(set! hunk-new-count (+ hunk-new-count 1))))
(set! new-pos (+ new-pos n)))))
(set! hunk-old-count (+ hunk-old-count 1))
(set! hunk-new-count (+ hunk-new-count 1))))
(Array.push-back! &hunks
(format-hunk hunk-old-start
hunk-old-count
hunk-new-start
hunk-new-count
&hunk-lines))
(set! in-hunk false)
(set! hunk-lines [])
(let-do [leading (Int.min ctx (- n trailing))
lead-start (- n leading)]
(set! lead-lines [])
(set! lead-count 0)
(set! lead-old-start (+ old-pos lead-start))
(set! lead-new-start (+ new-pos lead-start))
(for [j lead-start n]
(let-do [line (Array.unsafe-nth lines j)]
(Array.push-back! &lead-lines
(String.concat &[@" " @line]))
(set! lead-count (+ lead-count 1)))))))
(let-do [leading (Int.min ctx n)
lead-start (- n leading)]
(set! lead-lines [])
(set! lead-count 0)
(set! lead-old-start (+ old-pos lead-start))
(set! lead-new-start (+ new-pos lead-start))
(for [j lead-start n]
(let-do [line (Array.unsafe-nth lines j)]
(Array.push-back! &lead-lines
(String.concat &[@" " @line]))
(set! lead-count (+ lead-count 1))))))
(set! old-pos (+ old-pos n))
(set! new-pos (+ new-pos n)))
(Deletion lines)
(let-do [n (Array.length lines)]
(for [j 0 n]
(let-do [line (Array.unsafe-nth lines j)]
(Array.push-back! &hunk-lines (String.concat &[@"-" @line]))
(set! hunk-old-count (+ hunk-old-count 1))))
(set! old-pos (+ old-pos n)))
(Insertion lines)
(let-do [n (Array.length lines)]
(for [j 0 n]
(let-do [line (Array.unsafe-nth lines j)]
(Array.push-back! &hunk-lines (String.concat &[@"+" @line]))
(set! hunk-new-count (+ hunk-new-count 1))))
(set! new-pos (+ new-pos n))))))
(when in-hunk
(set! result
(emit-hunk result
hunk-old-start
hunk-old-count
hunk-new-start
hunk-new-count
&hunk-lines)))
result)))
(Array.push-back! &hunks
(format-hunk hunk-old-start
hunk-old-count
hunk-new-start
hunk-new-count
&hunk-lines)))
(String.concat &hunks)))

(doc unified "Renders a line diff in unified diff format with hunk headers.
Expects the output of `line-diff` or a diff of string arrays.
Uses 3 lines of context around changes.")
(defn unified [d] (unified-with-context d 3)))
72 changes: 71 additions & 1 deletion tests/diff.carp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -308,4 +308,74 @@ KK")) "unified generates multiple hunks for distant changes")
(assert-equal test
0.0
(Diff.similarity &[] &[1 2 3])
"similarity with one empty array is 0.0")))
"similarity with one empty array is 0.0")

; str/prn
(assert-equal test
"(Eq [1 2 3])"
&(str &(Eq [1 2 3]))
"str of Eq shows variant and contents")
(assert-equal test
"(Insertion [42])"
&(str &(Insertion [42]))
"str of Insertion shows variant and contents")
(assert-equal test
"(Deletion [7 8])"
&(str &(Deletion [7 8]))
"str of Deletion shows variant and contents")
(assert-equal test
"(Insertion [10 20])"
&(str &(Insertion [10 20]))
"str of Insertion with multiple elements")

; unified-with-context
(assert-equal test &(String.concat &[@"@@ -2,1 +2,1 @@
" @"+changed
" @"-line2
"]) &(unified-with-context &(line-diff "line1
line2
line3" "line1
changed
line3") 0) "unified-with-context 0 omits context lines")
(assert-equal test &(String.concat &[@"@@ -1,3 +1,3 @@
" @" line1
" @"+changed
" @"-line2
" @" line3
"]) &(unified-with-context &(line-diff "line1
line2
line3" "line1
changed
line3") 3) "unified-with-context 3 matches unified default")
(assert-equal test &(unified &(line-diff "line1
line2
line3" "line1
changed
line3")) &(unified-with-context &(line-diff "line1
line2
line3" "line1
changed
line3") 3) "unified-with-context 3 is identical to unified")
(assert-equal test &(String.concat &[@"@@ -1,3 +1,3 @@
" @" a
" @"+BB
" @"-b
" @" c
" @"@@ -5,3 +5,3 @@
" @" e
" @"+FF
" @"-f
" @" g
"]) &(unified-with-context &(line-diff "a
b
c
d
e
f
g" "a
BB
c
d
e
FF
g") 1) "unified-with-context 1 splits hunks with enough gap")))