From f8f9095fcaf3359c1290ce3def11390d7ef18d75 Mon Sep 17 00:00:00 2001
From: Horizontal42 <75383519+Horizontal42@users.noreply.github.com>
Date: Wed, 1 Jul 2026 20:27:55 +0300
Subject: [PATCH] add ISO date literals and days until/since

---
 src/engine/engine.test.ts | 18 ++++++++++++++++++
 src/engine/evaluator.ts   | 12 +++++++++++-
 src/engine/formatter.ts   |  2 ++
 src/engine/index.ts       |  3 ++-
 src/engine/lexer.ts       | 15 ++++++++++++++-
 src/engine/parser.ts      |  4 ++++
 src/engine/registry.ts    |  5 ++++-
 src/engine/tokenizer.ts   |  9 ++++++++-
 src/engine/vocab-data.ts  |  8 ++++++--
 src/ui/editor.ts          |  2 +-
 10 files changed, 70 insertions(+), 8 deletions(-)

diff --git a/src/engine/engine.test.ts b/src/engine/engine.test.ts
index 5501da9..9a37e9c 100644
--- a/src/engine/engine.test.ts
+++ b/src/engine/engine.test.ts
@@ -282,6 +282,24 @@ describe("dates", () => {
     const t = calc("time in Tokyo");
     expect(t).toMatch(/^\d{2}:\d{2}$/);
   });
+  it("ISO date literal produces a formatted date", () => {
+    const r = calc("2024-01-01");
+    expect(r).not.toBeNull();
+    expect(typeof r).toBe("string");
+  });
+  it("ISO date subtraction: 2026-01-01 - 2024-01-01 = 731 days", () => {
+    expect(calc("2026-01-01 - 2024-01-01")).toBe("731 day");
+  });
+  it("days until future date returns positive days", () => {
+    const r = calc("days until 2099-01-01");
+    expect(r).not.toBeNull();
+    expect(Number(r!.replace(/[^\d.-]/g, ""))).toBeGreaterThan(0);
+  });
+  it("days since past date returns positive days", () => {
+    const r = calc("days since 2000-01-01");
+    expect(r).not.toBeNull();
+    expect(Number(r!.replace(/[^\d.-]/g, ""))).toBeGreaterThan(0);
+  });
 });
 
 describe("extension API", () => {
diff --git a/src/engine/evaluator.ts b/src/engine/evaluator.ts
index 4eaf43f..13032aa 100644
--- a/src/engine/evaluator.ts
+++ b/src/engine/evaluator.ts
@@ -42,6 +42,8 @@ export function evaluate(node: Node, ctx: EvalCtx): Value {
     }
     case "date":
       return evalDateWord(node.word);
+    case "datelit":
+      return { kind: "date", ms: node.ms, hasTime: false };
     case "agg":
       return evalAgg(node.name, ctx);
     case "neg": {
@@ -192,7 +194,7 @@ function evalBin(op: "plus" | "minus" | "mul" | "div" | "mod" | "pow", l: Value,
       }
     }
     const q = (l.kind === "quantity" ? l : r) as Quantity;
-    const p = (l.kind === "percent" ? l : r).value;
+    const p = (l.kind === "percent" ? l : r as { kind: "percent"; value: Decimal }).value;
     switch (op) {
       case "plus": return qty(q.value.mul(new Decimal(1).add(p.div(100))), q.unit);
       case "minus":
@@ -513,6 +515,14 @@ function evalCall(name: string, args: Value[], ctx: EvalCtx): Value {
       const raw = isInt ? Math.floor(rand * (hi - lo + 1)) + lo : rand * (hi - lo) + lo;
       return qty(new Decimal(raw));
     }
+    case "until": {
+      if (x.kind !== "date") throw new EvalError("until needs a date");
+      return evalDateArith("minus", x, { kind: "date", ms: startOfToday(), hasTime: false });
+    }
+    case "since": {
+      if (x.kind !== "date") throw new EvalError("since needs a date");
+      return evalDateArith("minus", { kind: "date", ms: startOfToday(), hasTime: false }, x);
+    }
     default: throw new EvalError(`unknown function ${name}`);
   }
 }
diff --git a/src/engine/formatter.ts b/src/engine/formatter.ts
index 28fdf24..9c757f6 100644
--- a/src/engine/formatter.ts
+++ b/src/engine/formatter.ts
@@ -26,6 +26,8 @@ export function formatNumber(v: Decimal, s: EngineSettings): string {
 }
 
 export function formatValue(v: Value, s: EngineSettings): string {
+  if (v.kind === "chart") return "";
+
   if (v.kind === "percent") {
     return formatNumber(v.value, s) + "%";
   }
diff --git a/src/engine/index.ts b/src/engine/index.ts
index 8680bc2..9b6388b 100644
--- a/src/engine/index.ts
+++ b/src/engine/index.ts
@@ -211,7 +211,8 @@ export class SumEngine {
       return { double: v.value.toNumber(), ...(v.unit ? { unitId: v.unit.id } : {}) };
     }
     if (v.kind === "percent") return { double: v.value.div(100).toNumber() };
-    return { double: v.ms };
+    if (v.kind === "date") return { double: v.ms };
+    return { double: 0 }; // chart — not representable as ExtensionValue
   }
 }
 
diff --git a/src/engine/lexer.ts b/src/engine/lexer.ts
index a46af53..8fa9f3b 100644
--- a/src/engine/lexer.ts
+++ b/src/engine/lexer.ts
@@ -3,12 +3,13 @@
 import { Decimal, NumeralRepr } from "./types";
 
 export interface Lex {
-  type: "num" | "word" | "sym";
+  type: "num" | "word" | "sym" | "date";
   raw: string;
   start: number;
   end: number;
   value?: Decimal;
   repr?: NumeralRepr;
+  dateMs?: number;
 }
 
 const WORD_RE = /^[\p{L}_]+/u;
@@ -32,6 +33,18 @@ export function lexLine(text: string): Lex[] {
     }
     const rest = text.slice(i);
 
+    if (ch >= "0" && ch <= "9") {
+      const iso = /^\d{4}-\d{2}-\d{2}(?!\d)/.exec(rest);
+      if (iso) {
+        const [y, mo, d] = iso[0].split("-").map(Number);
+        const dt = new Date(y, mo - 1, d);
+        if (!isNaN(dt.getTime())) {
+          out.push({ type: "date", raw: iso[0], start: i, end: i + iso[0].length, dateMs: dt.getTime() });
+          i += iso[0].length;
+          continue;
+        }
+      }
+    }
     if (ch >= "0" && ch <= "9") {
       const hex = /^0[xX][0-9a-fA-F]+/.exec(rest);
       if (hex) {
diff --git a/src/engine/parser.ts b/src/engine/parser.ts
index 2737db0..5705cb2 100644
--- a/src/engine/parser.ts
+++ b/src/engine/parser.ts
@@ -19,6 +19,7 @@ export type Node =
   | { k: "const"; name: "pi" | "e" | "half" | "onehalf" }
   | { k: "var"; name: string }
   | { k: "date"; word: DateWord }
+  | { k: "datelit"; ms: number }
   | { k: "agg"; name: "sum" | "avg" | "prev" | "count" | "min" | "max" | "product" | "chart" }
   | { k: "bin"; op: "plus" | "minus" | "mul" | "div" | "mod" | "pow"; l: Node; r: Node }
   | { k: "bit"; op: BitOp; l: Node; r: Node }
@@ -360,6 +361,9 @@ class Parser {
       case "date":
         this.i++;
         return { k: "date", word: tk.word };
+      case "datelit":
+        this.i++;
+        return { k: "datelit", ms: tk.ms };
       case "agg":
         this.i++;
         return { k: "agg", name: tk.name };
diff --git a/src/engine/registry.ts b/src/engine/registry.ts
index 335a82e..7c646b2 100644
--- a/src/engine/registry.ts
+++ b/src/engine/registry.ts
@@ -58,7 +58,7 @@ const BUILTIN_FUNCS = [
   "sqrt", "cbrt", "sin", "cos", "tan", "cot", "asin", "acos", "atan",
   "arcsin", "arccos", "arctan", "sinh", "cosh", "tanh",
   "ln", "lg", "log", "log2", "exp", "abs", "round", "ceil", "floor",
-  "fact", "factorial", "random",
+  "fact", "factorial", "random", "until", "since",
 ];
 
 export class Registry {
@@ -181,6 +181,9 @@ export function buildRegistry(): Registry {
   for (const v of vocab.variants("Operations", "ln.variants")) reg.addPhrase(v, { t: "func", name: "ln" }, { caseSensitive: false });
   for (const v of vocab.variants("Operations", "log.variants")) reg.addPhrase(v, { t: "func", name: "log" }, { caseSensitive: false });
   for (const v of vocab.variants("Operations", "round.variants")) reg.addPhrase(v, { t: "func", name: "round" }, { caseSensitive: false });
+  for (const v of vocab.variants("Operations", "random.variants")) reg.addPhrase(v, { t: "func", name: "random" }, { caseSensitive: false });
+  for (const v of vocab.variants("Operations", "until.variants")) reg.addPhrase(v, { t: "func", name: "until" }, { caseSensitive: false });
+  for (const v of vocab.variants("Operations", "since.variants")) reg.addPhrase(v, { t: "func", name: "since" }, { caseSensitive: false });
   reg.addPhrase("mod", { t: "op", op: "mod" }, { caseSensitive: false });
   reg.addPhrase("modulo", { t: "op", op: "mod" }, { caseSensitive: false });
 
diff --git a/src/engine/tokenizer.ts b/src/engine/tokenizer.ts
index 8a0ef5f..1a7c5cc 100644
--- a/src/engine/tokenizer.ts
+++ b/src/engine/tokenizer.ts
@@ -15,10 +15,11 @@ export type Token =
   | { t: "pctop"; op: PctOp; start: number; end: number }
   | { t: "percent"; start: number; end: number }
   | { t: "func"; name: string; start: number; end: number }
-  | { t: "agg"; name: "sum" | "avg" | "prev"; start: number; end: number }
+  | { t: "agg"; name: "sum" | "avg" | "prev" | "count" | "min" | "max" | "product" | "chart"; start: number; end: number }
   | { t: "scale"; mult: Decimal; start: number; end: number }
   | { t: "repr"; repr: NumeralRepr; start: number; end: number }
   | { t: "date"; word: DateWord; start: number; end: number }
+  | { t: "datelit"; ms: number; start: number; end: number }
   | { t: "const"; name: "pi" | "e" | "half" | "onehalf"; start: number; end: number }
   | { t: "lparen"; start: number; end: number }
   | { t: "rparen"; start: number; end: number }
@@ -45,6 +46,12 @@ export function tokenize(line: string, reg: Registry): Token[] {
       continue;
     }
 
+    if (lx.type === "date") {
+      tokens.push({ t: "datelit", ms: lx.dateMs!, ...span });
+      i++;
+      continue;
+    }
+
     const m = reg.match(lexes, lowers, i);
     if (m) {
       const end = lexes[i + m.length - 1].end;
diff --git a/src/engine/vocab-data.ts b/src/engine/vocab-data.ts
index 2b58106..aaebe90 100644
--- a/src/engine/vocab-data.ts
+++ b/src/engine/vocab-data.ts
@@ -433,7 +433,9 @@ export const EN: VocabLocale = {
     "max.variants": "max,maximum,largest",
     "product.variants": "product",
     "random.variants": "random,rand",
-    "chart.variants": "chart,spark,sparkline,graph"
+    "chart.variants": "chart,spark,sparkline,graph",
+    "until.variants": "until,days until,day until",
+    "since.variants": "since,days since,day since"
   },
   "Percent": {
     "as_a_percent_of.variants": "as a % of,as a percent of",
@@ -911,7 +913,9 @@ export const RU: VocabLocale = {
     "max.variants": "максимум,макс,наибольшее",
     "product.variants": "произведение,произв",
     "random.variants": "случайное,случайно,рандом",
-    "chart.variants": "график,спарклайн,диаграмма"
+    "chart.variants": "график,спарклайн,диаграмма",
+    "until.variants": "осталось до,дней до,дней до даты",
+    "since.variants": "прошло с,дней с,дней прошло с"
   },
   "Percent": {
     "as_a_percent_of.variants": "как процент от,как процент",
diff --git a/src/ui/editor.ts b/src/ui/editor.ts
index dcb1698..79dbdb1 100644
--- a/src/ui/editor.ts
+++ b/src/ui/editor.ts
@@ -40,7 +40,7 @@ function buildDecorations(state: EditorState): DecorationSet {
       let cls: string | null = null;
       switch (tk.t) {
         case "num": case "const": case "scale": cls = "tok-number"; break;
-        case "unit": case "currency": case "repr": case "date": cls = "tok-unit"; break;
+        case "unit": case "currency": case "repr": case "date": case "datelit": cls = "tok-unit"; break;
         case "op": case "conv": case "assign": case "pctop": case "percent": case "bang": cls = "tok-op"; break;
         case "func": case "agg": cls = "tok-var"; break;
         default: cls = null;