fix: various metadata preservation issues (boxing, LaTeX-parsing)

src/compute-engine/boxed-expression/box.ts

@@ -8,8 +8,16 @@ import {
   CanonicalOptions,
 } from './public';
 
-import { Expression, MathJsonIdentifier } from '../../math-json/types';
-import { machineValue, missingIfEmpty } from '../../math-json/utils';
+import {
+  Expression,
+  ExpressionObject,
+  MathJsonIdentifier,
+} from '../../math-json/types';
+import {
+  hasMetaData,
+  machineValue,
+  missingIfEmpty,
+} from '../../math-json/utils';
 import {
   isValidIdentifier,
   validateIdentifier,
@@ -164,7 +172,7 @@ export function boxFunction(
     return ce._fn(
       name,
       ops.map((x) => ce.box(x, { canonical: false })),
-      options.metadata
+      { metadata: options.metadata }
     );
   }
 
@@ -384,16 +392,22 @@ export function box(
   // Box a MathJSON object literal
   //
   if (typeof expr === 'object') {
+    const metadata = hasMetaData(expr as ExpressionObject)
+      ? ({
+          latex: (expr as ExpressionObject).latex,
+          wikidata: (expr as ExpressionObject).wikidata,
+        } satisfies Metadata)
+      : undefined;
     if ('fn' in expr) {
       const [fnName, ...ops] = expr.fn;
       return canonicalForm(
-        boxFunction(ce, fnName, ops, { canonical, structural }),
+        boxFunction(ce, fnName, ops, { canonical, structural, metadata }),
         options.canonical!
       );
     }
-    if ('str' in expr) return new BoxedString(ce, expr.str);
-    if ('sym' in expr) return ce.symbol(expr.sym, { canonical });
-    if ('num' in expr) return ce.number(expr, { canonical });
+    if ('str' in expr) return new BoxedString(ce, expr.str, metadata);
+    if ('sym' in expr) return ce.symbol(expr.sym, { canonical, metadata });
+    if ('num' in expr) return ce.number(expr, { canonical, metadata });
 
     throw new Error(`Unexpected MathJSON object: ${JSON.stringify(expr)}`);
   }
@@ -481,7 +495,7 @@ function makeCanonicalFunction(
     return ce._fn(
       name,
       validateArguments(ce, xs, def.signature, def.lazy, def.threadable) ?? xs,
-      metadata
+      { metadata }
     );
   }
 
@@ -528,7 +542,7 @@ function makeCanonicalFunction(
 
   // If we have some adjusted arguments, the arguments did not
   // match the parameters of the signature. We're done.
-  if (adjustedArgs) return ce._fn(name, adjustedArgs, metadata);
+  if (adjustedArgs) return ce._fn(name, adjustedArgs, { metadata });
 
   //
   // 4/ Apply `idempotent` and `involution`
@@ -538,14 +552,14 @@ function makeCanonicalFunction(
     if (def.involution) return args[0].op1;
 
     // f(f(x)) -> f(x)
-    if (def.idempotent) return ce._fn(name, xs[0].ops!, metadata);
+    if (def.idempotent) return ce._fn(name, xs[0].ops!, { metadata });
   }
 
   //
   // 5/ Sort the operands
   //
 
-  return ce._fn(name, sortOperands(name, args), metadata);
+  return ce._fn(name, sortOperands(name, args), { metadata });
 }
 
 function makeNumericFunction(
@@ -581,7 +595,7 @@ function makeNumericFunction(
 
   // If some of the arguments are not valid, we're done
   // (note: the result is canonical, but not valid)
-  if (!ops.every((x) => x.isValid)) return ce._fn(name, ops, metadata);
+  if (!ops.every((x) => x.isValid)) return ce._fn(name, ops, { metadata });
 
   //
   // Short path for some functions
@@ -606,10 +620,10 @@ function makeNumericFunction(
       // Ln(1) -> 0, Log(1) -> 0
       if (ops[0].is(1)) return ce.Zero;
       // Ln(a) -> Ln(a), Log(a) -> Log(a)
-      if (ops.length === 1) return ce._fn(name, ops, metadata);
+      if (ops.length === 1) return ce._fn(name, ops, { metadata });
     }
     // Ln(a,b) -> Log(a, b)
-    return ce._fn('Log', ops, metadata);
+    return ce._fn('Log', ops, { metadata });
   }
 
   return null;

src/compute-engine/boxed-expression/public.ts

@@ -1,5 +1,6 @@
 import { Complex } from 'complex-esm';
 import type {
+  Attributes,
   Expression,
   MathJsonNumber,
   MathJsonString,
@@ -2036,10 +2037,7 @@ export type EvaluateOptions = {
  * @category Boxed Expression
  */
 
-export type Metadata = {
-  latex?: string | undefined;
-  wikidata?: string | undefined;
-};
+export type Metadata = Pick<Attributes, 'latex' | 'wikidata'>;
 
 /**
  * When a unitless value is passed to or returned from a trigonometric function,
@@ -2277,7 +2275,7 @@ export interface IComputeEngine extends IBigNum {
   _fn(
     name: string,
     ops: ReadonlyArray<BoxedExpression>,
-    options?: Metadata & { canonical?: boolean }
+    options?: { canonical?: boolean; metadata?: Metadata }
   ): BoxedExpression;
 
   parse(

src/compute-engine/compute-engine.ts

@@ -1924,7 +1924,7 @@ export class ComputeEngine implements IComputeEngine {
       return this._fn(
         'Rational',
         [this.number(value[0]), this.number(value[1])],
-        { ...metadata, canonical: false }
+        { metadata, canonical: false }
       );
     }
 
@@ -2015,10 +2015,13 @@ export class ComputeEngine implements IComputeEngine {
   _fn(
     name: MathJsonIdentifier,
     ops: ReadonlyArray<BoxedExpression>,
-    options?: Metadata & { canonical?: boolean }
+    options?: { canonical?: boolean; metadata?: Metadata }
   ): BoxedExpression {
     const canonical = options?.canonical ?? true;
-    return new BoxedFunction(this, name, ops, { ...options, canonical });
+    return new BoxedFunction(this, name, ops, {
+      metadata: options?.metadata,
+      canonical,
+    });
   }
 
   /**

src/compute-engine/latex-syntax/parse.ts

@@ -2046,7 +2046,11 @@ export class _Parser implements Parser {
     } else if (typeof expr === 'number') {
       expr = { latex, num: Number(expr).toString() };
     } else if (typeof expr === 'string') {
-      expr = { latex, sym: expr };
+      if (expr.startsWith("'")) {
+        expr = { str: expr.slice(1, -1) };
+      } else {
+        expr = { sym: expr };
+      }
     } else if (typeof expr === 'object' && expr !== null) {
       (expr as ExpressionObject).latex = latex;
     }

src/math-json/utils.ts

@@ -1,5 +1,7 @@
 import type {
+  Attributes,
   Expression,
+  ExpressionObject,
   MathJsonFunction,
   MathJsonIdentifier,
   MathJsonNumber,
@@ -41,6 +43,40 @@ export function isFunctionObject(
   return expr !== null && typeof expr === 'object' && 'fn' in expr;
 }
 
+export function isExpressionObject(
+  expr: Expression | null
+): expr is ExpressionObject {
+  const isObj = expr !== null && typeof expr === 'object';
+  return (
+    isObj && ('fn' in expr || 'num' in expr || 'sym' in expr || 'str' in expr)
+  );
+}
+
+/**
+ * →true if Expression **expr** has *at least one* recognized meta-property key with its
+ * corresponding value non-'undefined'. Naturally, this also entails that *expr* is an
+ * 'ExpressionObject' variant of 'Expression'.
+ *
+ */
+export function hasMetaData(expr: Expression): expr is ExpressionObject {
+  return (
+    isExpressionObject(expr) &&
+    (hasMetaProperty(expr, 'latex') || hasMetaProperty(expr, 'wikidata'))
+  );
+}
+
+/**
+ * Returns true if meta prop. *key* is present in *expr* & this propery's value is also
+ * non-'undefined'.
+ *
+ */
+export function hasMetaProperty<
+  E extends ExpressionObject,
+  K extends keyof Pick<Attributes, 'latex' | 'wikidata'>,
+>(expr: E, key: K): expr is E & { [k in K]: NonNullable<ExpressionObject[K]> } {
+  return expr[key] !== undefined;
+}
+
 /**  If expr is a string literal, return it.
  *
  * A string literal is a JSON string that begins and ends with