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fix(lsp): preserve body alignment after tuple commas #1833

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Merged
Lorenzobattistela merged 2 commits into from
Oct 23, 2026
Merged

fix(lsp): preserve body alignment after tuple commas #1833

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e4243b4
fix(lsp): preserve body alignment after tuple commas
vicmcorrea Oct 23, 2026
68ac6c5
test(lsp): cover continued tuple items and following arguments
vicmcorrea Oct 23, 2026
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12 changes: 10 additions & 2 deletions tools/bend-fmt-lsp/src/formatter.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -167,11 +167,13 @@ type BodyScope = { open: number; angle: number; end: number };
type InlineBody = { at: number; scope?: BodyScope };

// The tokens that start a body on the line of its `do`, `match`, `case` or
// `def` header, `=>` lambda opener, `;` separator or `(` group opener. As in
// `do IO<Unit>: a`, Bend pins the lines after it to the column of `a`.
// `def` header, `=>` lambda opener, `;` separator, `(` group opener or
// parenthesized `,` separator. As in `do IO<Unit>: a`, Bend pins the lines
// after it to the column of `a`.
function inlineBodies(lines: Line[]): InlineBody[][] {
let open = 0;
const angles = [0];
const parens: number[] = [];
const bodyScopes: BodyScope[] = [];
let header: { open: number; angle: number; typed: boolean } | null = null;
return lines.map((line, row) => line.tokens.flatMap((token, index): InlineBody[] => {
Expand All @@ -183,11 +185,13 @@ function inlineBodies(lines: Line[]): InlineBody[][] {
} else if (["(", "[", "{"].includes(token.text)) {
open++;
angles.push(0);
if (token.text === "(") parens.push(open);
if (token.text === "(" && index + 1 < line.tokens.length) {
bodyScopes.push({ open, angle: angles[open], end: lines.length });
return [{ at: index + 1, scope: bodyScopes.at(-1) }];
}
} else if ([")", "]", "}"].includes(token.text)) {
if (parens.at(-1) === open) parens.pop();
if (open > 0) angles.pop();
open = Math.max(0, open - 1);
} else if (ANGLES.has(token.text)) {
Expand All @@ -209,6 +213,10 @@ function inlineBodies(lines: Line[]): InlineBody[][] {
// A leading closer/separator has no body statement to pin on this line.
bodyScopes.pop()!.end = row - (index === 0 ? 1 : 0);
}
if (token.text === "," && parens.at(-1) === open && angles[open] === 0 && index + 1 < line.tokens.length) {
bodyScopes.push({ open, angle: angles[open], end: lines.length });
return [{ at: index + 1, scope: bodyScopes.at(-1) }];
}
return [];
}));
}
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11 changes: 10 additions & 1 deletion tools/bend-fmt-lsp/src/test/formatter.test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -8,7 +8,8 @@ import { fileURLToPath } from "node:url";
import { formatBend } from "../formatter.js";

// Bend pins the lines after a body that shares a line with its `do`, `match`,
// `case` or `def` header, `=>` lambda opener or `;` to that body's column. [source, formatted]
// `case` or `def` header, `=>` lambda opener, `;`, `(` or parenthesized `,`
// to that body's column. [source, formatted]
const pinned = [
[
"import Base\ndef f(a:Array<U32>)->Array<U32>: b=a; b[0]<-7\n b[1]<-8\n\ndef main() -> Array<U32>:\n f([0 : U32 * 2n])\n",
Expand Down Expand Up @@ -76,6 +77,14 @@ const pinned = [
"import Base\ndef f(a: Array<U32>, b: Bool, c: Bool) -> Array<U32>:\n match b:\n case True{}: match c:\n case True{}: a[0] <- 7\n a[1] <- 8\n case False{}: a\n case False{}: a\n\ndef main() -> Array<U32>:\n f([0 : U32*2n], True{}, True{})\n",
"import Base\ndef f(a: Array<U32>, b: Bool, c: Bool) -> Array<U32>:\n match b:\n case True{}: match c:\n case True{}: a[0] <- 7\n a[1] <- 8\n case False{}: a\n case False{}: a\n\ndef main() -> Array<U32>:\n f([0 : U32 * 2n], True{}, True{})\n",
],
[
"import Base\ndef main()->U32 & Array<U32>:\n a = [0 : U32 * 2n]\n (17,a[0]<-3\n a[1]<-5)\n",
"import Base\ndef main() -> U32 & Array<U32>:\n a = [0 : U32 * 2n]\n (17, a[0] <- 3\n a[1] <- 5)\n",
],
[
"import Base\ndef finish(p:U32 & Array<U32>,n:U32)->Array<U32>:\n (x,a) = p\n a[0] <- U32.add(x,n)\ndef main()->Array<U32>:\n a = [0 : U32 * 2n]\n finish((17,a[0]<-3\n a[1]<-5),\n 11)\n",
"import Base\ndef finish(p: U32 & Array<U32>, n: U32) -> Array<U32>:\n (x, a) = p\n a[0] <- U32.add(x, n)\ndef main() -> Array<U32>:\n a = [0 : U32 * 2n]\n finish((17, a[0] <- 3\n a[1] <- 5),\n 11)\n",
],
];

test("moves pinned lines as far as the body they line up with", () => {
Expand Down