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feat(mark): more robust checkpoint handling
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@MKRhere
MKRhere committed Jan 8, 2025
1 parent cfefbca commit 6352808
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Showing 5 changed files with 139 additions and 109 deletions.
14 changes: 11 additions & 3 deletions packages/mark/src/Context.ts
View file
Original file line number Diff line number Diff line change
Expand Up @@ -58,9 +58,17 @@ export class ParserContext {
return this.input.slice(this.index + offset, this.index + offset + count);
}

revert(index: number): undefined {
this.index = index;
return undefined;
checkpoint() {
const i = this.index;
const l = this.line;
const c = this.column;

return (): undefined => {
this.index = i;
this.line = l;
this.column = c;
return undefined;
};
}

eof() {
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172 changes: 92 additions & 80 deletions packages/mark/src/block.ts
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,8 @@ import { ident, try_param_value } from "./value.ts";
import { inline } from "./inline.ts";

export function param(ctx: ParserContext): Block.Parameter | undefined {
const revert = ctx.checkpoint();

const name = ident(ctx);
if (!name) return undefined;

Expand All @@ -13,19 +15,21 @@ export function param(ctx: ParserContext): Block.Parameter | undefined {
ctx.nomnomnom();

const value = try_param_value(ctx);
if (value === undefined) throw ctx.error("value", ctx.peek());
if (value === undefined) return revert();

return new Block.Parameter(name, value);
}

export function callNotation(
ctx: ParserContext,
type: "@" | "=",
): Block.Call | Block.Decorator | Meta {
): Block.Call | Block.Decorator | undefined {
const revert = ctx.checkpoint();

ctx.nomnom();

const name = ident(ctx);
if (!name) throw ctx.error("identifier", ctx.peek());
if (!name) return revert();
ctx.nomnom();

const has_params = ctx.consume_if("(");
Expand All @@ -44,7 +48,7 @@ export function callNotation(
while (ctx.not(")")) {
ctx.nomnomnom();

if (ctx.eof()) throw ctx.error(")", "EOF");
if (ctx.eof()) return revert();

// expect a comma if not the first value
// trailing commas are required at the moment
Expand All @@ -61,12 +65,11 @@ export function callNotation(
}
}

if (ctx.not(")")) throw ctx.error(")", ctx.peek());
if (ctx.not(")")) return revert();
ctx.consume(); // consume the closing parenthesis
}

if (type === "@") return new Block.Decorator(name, params, []);
else if (name === "meta") return new Meta(params);
else return new Block.Call(name, params);
}

Expand Down Expand Up @@ -102,6 +105,7 @@ export function codeblock(ctx: ParserContext) {
.filter((x): x is NonNullable<typeof x> => x !== undefined);
else if (key === "end") code_params.end = value;
} else if (!code_params.title) code_params.title = param;
// TODO: think of a way to gracefully handle this
else throw ctx.error("valid codeblock parameter", param);
}

Expand All @@ -111,7 +115,7 @@ export function codeblock(ctx: ParserContext) {
// loop as along as we don't find the end of the codeblock
// the end is automatically consumed by consume_if
while (!ctx.consume_if(end_string)) {
if (ctx.eof()) throw ctx.error("end of codeblock", "EOF");
if (ctx.eof()) break; // just allow EOF to be the end of the codeblock
content += ctx.consume();
}

Expand All @@ -120,10 +124,12 @@ export function codeblock(ctx: ParserContext) {
return new Block.CodeBlock(content, code_params);
}

export function heading(ctx: ParserContext) {
export function heading(ctx: ParserContext): Block.Heading | undefined {
const revert = ctx.checkpoint();

let level = 0;
while (ctx.consume_if("#")) level++;
if (level < 1 || level > 6) throw ctx.error("heading level 1-6", ctx.peek());
if (level < 1 || level > 6) return revert();
const content = inline(ctx, "\n");
return new Block.Heading(level as Block.HeadingLevel, content);
}
Expand Down Expand Up @@ -169,18 +175,18 @@ export function para(ctx: ParserContext) {
}

export function footnote(ctx: ParserContext) {
let checkpoint = ctx.index;
const revert = ctx.checkpoint();

let reference = "";
while (ctx.not("]", "\n")) {
if (ctx.eof()) return ctx.revert(checkpoint);
if (ctx.eof()) return revert();
reference += ctx.consume();
}

if (ctx.not("]")) return ctx.revert(checkpoint);
if (ctx.not("]")) return revert();
ctx.consume(); // consume the closing bracket

if (!ctx.consume_if(":")) return ctx.revert(checkpoint);
if (!ctx.consume_if(":")) return revert();

ctx.nomnom();

Expand Down Expand Up @@ -224,22 +230,22 @@ export function quote(ctx: ParserContext): Block.Quote | undefined {
}

export function try_alignment(ctx: ParserContext): Block.TableAlignment | undefined {
const checkpoint = ctx.index;
const revert = ctx.checkpoint();

let buffer = "";
while (ctx.is(":", "-")) buffer += ctx.consume();

if (buffer.length === 0) return ctx.revert(checkpoint);
if (buffer.length === 0) return revert();

if (/^:?-+$/.test(buffer)) return "left";
if (/^-+:$/.test(buffer)) return "right";
if (/^:-+:$/.test(buffer)) return "center";

return ctx.revert(checkpoint);
return revert();
}

export function table(ctx: ParserContext): Block.Table | undefined {
const checkpoint = ctx.index;
const revert = ctx.checkpoint();

let header: Block.TableRow | undefined = undefined;
const rows: Block.TableRow[] = [];
Expand Down Expand Up @@ -282,7 +288,7 @@ export function table(ctx: ParserContext): Block.Table | undefined {
}

const content = inline(ctx, "|");
if (ctx.not("|")) return ctx.revert(checkpoint);
if (ctx.not("|")) return revert();

row.cells.push(new Block.TableCell(content));
}
Expand Down Expand Up @@ -376,65 +382,6 @@ export function list(ctx: ParserContext): Block.List {
return new Block.List(items);
}

export function parse_block(
ctx: ParserContext,
is_top_level: boolean,
): (Block | DecoratorEndMarker | DecoratorStartMarker)[] | undefined {
if (ctx.eof()) return undefined;

const char = ctx.peek();

switch (char) {
case "\n":
ctx.consume();
return undefined;
case "<":
if (ctx.consume_if("<@")) return [new DecoratorEndMarker()];
return [para(ctx)];
case "\\":
return [para(ctx)];
case "=": {
ctx.consume();
const result = callNotation(ctx, "=");
if (is_top_level && result instanceof Meta) {
if (ctx.doc.blocks.length)
throw ctx.unexpected("=meta() call. Meta can only be declared at the top of a document");
ctx.doc.meta = result;
return undefined;
}
return [result as Block.Call];
}
case "@": {
ctx.consume();
const result = callNotation(ctx, "@") as Block.Decorator;
if (ctx.consume_if(">")) {
ctx.nomnomnom();
return [result, new DecoratorStartMarker()];
}
return [result];
}
case "#":
return [heading(ctx)];
case "`":
return [ctx.peek(0, 3) === "```" ? codeblock(ctx) : para(ctx)];
case ">":
return [quote(ctx) ?? para(ctx)];
case "|":
return [table(ctx) ?? para(ctx)];
case "[":
return [ctx.consume_if("[^") ? footnote(ctx) ?? para(ctx) : para(ctx)];
case "-":
if (ctx.consume_if("---\n")) return [new Block.Rule()];
if (ctx.consume_if("--")) return [comment(ctx)];
if (ctx.is("- ")) return [list(ctx)];
return [para(ctx)];
default:
// Check for ordered lists
if (/^\d+\.\s/.test(ctx.peek(0, 4))) return [list(ctx)];
return [para(ctx)];
}
}

export function parse_blocks<T extends boolean>(
ctx: ParserContext,
is_top_level: T,
Expand All @@ -443,9 +390,74 @@ export function parse_blocks<T extends boolean>(

// Replace the main loop with the new version that handles arrays
while (!ctx.eof()) {
const block_or_blocks = parse_block(ctx, is_top_level);
if (block_or_blocks) {
blocks.push(...block_or_blocks);
const char = ctx.peek();

switch (char) {
case "\n":
ctx.consume();
continue;
case "<":
if (ctx.consume_if("<@")) {
blocks.push(new DecoratorEndMarker());
continue;
}
blocks.push(para(ctx));
continue;
case "\\":
blocks.push(para(ctx));
continue;
case "=": {
ctx.consume();
const result = callNotation(ctx, "=");
if (is_top_level && result?.type === "call" && result.name === "meta") {
if (ctx.doc.blocks.length)
throw ctx.unexpected(
"=meta() call. Meta can only be declared once at the top of a document",
);
ctx.doc.meta = new Meta(result.parameters);
continue;
}
blocks.push(result ?? para(ctx));
continue;
}
case "@": {
ctx.consume();
const result = callNotation(ctx, "@") as Block.Decorator;
if (ctx.consume_if(">")) {
ctx.nomnomnom();
blocks.push(result);
blocks.push(new DecoratorStartMarker());
continue;
}
blocks.push(result);
continue;
}
case "#":
blocks.push(heading(ctx) ?? para(ctx));
continue;
case "`":
blocks.push(ctx.peek(0, 3) === "```" ? codeblock(ctx) : para(ctx));
continue;
case ">":
blocks.push(quote(ctx) ?? para(ctx));
continue;
case "|":
blocks.push(table(ctx) ?? para(ctx));
continue;
case "[":
blocks.push(ctx.consume_if("[^") ? footnote(ctx) ?? para(ctx) : para(ctx));
continue;
case "-":
if (ctx.consume_if("---\n")) blocks.push(new Block.Rule());
else if (ctx.consume_if("--")) blocks.push(comment(ctx));
else if (ctx.is("- ")) blocks.push(list(ctx));
else blocks.push(para(ctx));
continue;
default:
// Check for ordered lists
if (/^\d+\.\s/.test(ctx.peek(0, 4))) blocks.push(list(ctx));
blocks.push(para(ctx));
continue;
}
}

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