Port round-trip bug fixes from Python ZON PR#9 to TypeScript

src/__tests__/boolean-keys.test.ts

@@ -0,0 +1,127 @@
+/**
+ * Tests for boolean-like dictionary keys.
+ *
+ * Verifies the fix for a bug where dictionary keys like "f", "t",
+ * "true", "false", "null" were incorrectly parsed as boolean/null values
+ * instead of being preserved as strings.
+ *
+ * Fixtures wrap the boolean-like key inside a nested object or array-of-objects
+ * so that encode/decode exercises _formatZonNode / _parseKey — the code paths
+ * that contain the actual fix.
+ */
+
+import { encode, decode } from '../index';
+
+describe('Boolean-like dictionary keys', () => {
+  test('Key "f" should not become false', () => {
+    const data = { wrapper: { f: 1 } };
+    const encoded = encode(data);
+    const decoded = decode(encoded) as any;
+    expect(decoded.wrapper).toEqual({ f: 1 });
+    expect(Object.keys(decoded.wrapper)).toContain('f');
+    expect(Object.keys(decoded.wrapper)).not.toContain('false');
+  });
+
+  test('Key "t" should not become true', () => {
+    const data = { wrapper: { t: 1 } };
+    const encoded = encode(data);
+    const decoded = decode(encoded) as any;
+    expect(decoded.wrapper).toEqual({ t: 1 });
+    expect(Object.keys(decoded.wrapper)).toContain('t');
+    expect(Object.keys(decoded.wrapper)).not.toContain('true');
+  });
+
+  test('Key "true" should not become boolean true', () => {
+    const data = { wrapper: { true: 1 } };
+    const encoded = encode(data);
+    const decoded = decode(encoded) as any;
+    expect(decoded.wrapper).toEqual({ true: 1 });
+    expect(Object.keys(decoded.wrapper)).toContain('true');
+  });
+
+  test('Key "false" should not become boolean false', () => {
+    const data = { wrapper: { false: 1 } };
+    const encoded = encode(data);
+    const decoded = decode(encoded) as any;
+    expect(decoded.wrapper).toEqual({ false: 1 });
+    expect(Object.keys(decoded.wrapper)).toContain('false');
+  });
+
+  test('Key "null" should not become null', () => {
+    const data = { wrapper: { null: 1 } };
+    const encoded = encode(data);
+    const decoded = decode(encoded) as any;
+    expect(decoded.wrapper).toEqual({ null: 1 });
+    expect(Object.keys(decoded.wrapper)).toContain('null');
+  });
+
+  test('Key "none" should not become null', () => {
+    const data = { wrapper: { none: 1 } };
+    const encoded = encode(data);
+    const decoded = decode(encoded) as any;
+    expect(decoded.wrapper).toEqual({ none: 1 });
+    expect(Object.keys(decoded.wrapper)).toContain('none');
+  });
+
+  test('Key "nil" should not become null', () => {
+    const data = { wrapper: { nil: 1 } };
+    const encoded = encode(data);
+    const decoded = decode(encoded) as any;
+    expect(decoded.wrapper).toEqual({ nil: 1 });
+    expect(Object.keys(decoded.wrapper)).toContain('nil');
+  });
+
+  test('Case variants of boolean-like keys are preserved', () => {
+    const cases: Array<[string, Record<string, number>]> = [
+      ['F', { F: 1 }],
+      ['T', { T: 1 }],
+      ['True', { True: 1 }],
+      ['False', { False: 1 }],
+      ['TRUE', { TRUE: 1 }],
+      ['FALSE', { FALSE: 1 }],
+      ['NULL', { NULL: 1 }],
+      ['NONE', { NONE: 1 }],
+      ['Null', { Null: 1 }],
+    ];
+    for (const [keyName, inner] of cases) {
+      const data = { wrapper: inner };
+      const encoded = encode(data);
+      const decoded = decode(encoded) as any;
+      expect(Object.keys(decoded.wrapper)).toContain(keyName);
+      expect(decoded.wrapper[keyName]).toBe(1);
+    }
+  });
+
+  test('Multiple boolean-like keys in same nested object', () => {
+    const data = { wrapper: { t: 1, f: 2, true: 3, false: 4, null: 5 } };
+    const encoded = encode(data);
+    const decoded = decode(encoded) as any;
+    expect(decoded.wrapper.t).toBe(1);
+    expect(decoded.wrapper.f).toBe(2);
+    expect(decoded.wrapper.true).toBe(3);
+    expect(decoded.wrapper.false).toBe(4);
+    expect(decoded.wrapper.null).toBe(5);
+  });
+
+  test('Nested object with boolean-like key round-trips', () => {
+    const data = { a: { b: { c: { d: { e: { f: 1 } } } } } };
+    const encoded = encode(data);
+    const decoded = decode(encoded) as any;
+    expect(decoded).toEqual(data);
+    const inner = decoded?.a?.b?.c?.d?.e;
+    expect(Object.keys(inner)).toContain('f');
+    expect(Object.keys(inner)).not.toContain('false');
+  });
+
+  test('Multiple sibling objects each with a boolean-like key round-trip', () => {
+    const data = { a: { f: 1 }, b: { t: 2 }, c: { null: 3 } };
+    const encoded = encode(data);
+    const decoded = decode(encoded) as any;
+    expect(Object.keys(decoded.a)).toContain('f');
+    expect(decoded.a.f).toBe(1);
+    expect(Object.keys(decoded.b)).toContain('t');
+    expect(decoded.b.t).toBe(2);
+    expect(Object.keys(decoded.c)).toContain('null');
+    expect(decoded.c.null).toBe(3);
+  });
+});

src/__tests__/dict-header-quoting.test.ts

@@ -0,0 +1,59 @@
+/**
+ * Tests for dictionary header value quoting.
+ *
+ * Verifies the fix for a bug where dictionary compression header values
+ * containing commas or colons were truncated at the delimiter, causing
+ * incorrect round-trips.
+ */
+
+import { encode, decode } from '../index';
+
+describe('Dictionary header value quoting', () => {
+  test('Dictionary values with commas round-trip correctly', () => {
+    const data = [
+      { Car: 'Toyota Celica ST 185', Year: '1996' },
+      { Car: 'Toyota Corolla, AWD', Year: '1997' },
+      { Car: 'Toyota Corolla, AWD', Year: '1998' },
+      { Car: 'Toyota Corolla, AWD', Year: '1999' },
+      { Car: 'Toyota Corolla, AWD', Year: '2000' },
+      { Car: 'Toyota Corolla, AWD', Year: '2001' },
+    ];
+    const encoded = encode(data);
+    const decoded = decode(encoded) as any[];
+    expect(decoded[0].Car).toBe('Toyota Celica ST 185');
+    expect(decoded[1].Car).toBe('Toyota Corolla, AWD');
+    expect(decoded[1].Year).toBe('1997');
+  });
+
+  test('Dictionary values with colons round-trip correctly', () => {
+    const data = [
+      { key: 'value:one', other: 'a' },
+      { key: 'value:one', other: 'b' },
+      { key: 'value:one', other: 'c' },
+      { key: 'value:one', other: 'd' },
+      { key: 'value:one', other: 'e' },
+      { key: 'value:two', other: 'f' },
+    ];
+    const encoded = encode(data);
+    const decoded = decode(encoded) as any[];
+    expect(decoded[0].key).toBe('value:one');
+    expect(decoded[5].key).toBe('value:two');
+  });
+
+  test('All rows preserved after dictionary decompression', () => {
+    const data = [
+      { Car: 'Toyota Celica ST 185', Year: '1996' },
+      { Car: 'Toyota Corolla, AWD', Year: '1997' },
+      { Car: 'Toyota Corolla, AWD', Year: '1998' },
+      { Car: 'Toyota Corolla, AWD', Year: '1999' },
+      { Car: 'Toyota Corolla, AWD', Year: '2000' },
+      { Car: 'Toyota Corolla, AWD', Year: '2001' },
+    ];
+    const encoded = encode(data);
+    const decoded = decode(encoded) as any[];
+    expect(decoded).toHaveLength(data.length);
+    for (let i = 0; i < data.length; i++) {
+      expect(decoded[i]).toEqual(data[i]);
+    }
+  });
+});

src/core/decoder.ts

@@ -1,6 +1,6 @@
 import { TABLE_MARKER, META_SEPARATOR, MAX_DOCUMENT_SIZE, MAX_LINE_LENGTH, MAX_ARRAY_LENGTH, MAX_OBJECT_KEYS, MAX_NESTING_DEPTH } from './constants';
 import { ZonDecodeError } from './exceptions';
-import { parseValue } from './utils';
+import { parseValue, parseKey } from './utils';
 import { extractVersion, stripVersion, type ZonDocumentMetadata } from './versioning';
 
 export interface DecodeOptions {
@@ -94,7 +94,7 @@ export class ZonDecoder {
       const dictMatch = trimmedLine.match(/^([\w\.]+)\[(\d+)\]:(.+)$/);
       if (dictMatch && !trimmedLine.startsWith(TABLE_MARKER)) {
         const [, col, , vals] = dictMatch;
-        pendingDictionaries.set(col, vals.split(','));
+        pendingDictionaries.set(col, this._splitByDelimiter(vals, ',').map(v => this._parseValue(v)));
         continue;
       }
 
@@ -612,7 +612,7 @@ export class ZonDecoder {
           continue;
         }
 
-        const key = this._parseValue(keyStr);
+        const key = this._parseKey(keyStr);
         const val = this._parseZonNode(valStr, depth + 1);
         obj[key] = val;
       }
@@ -745,7 +745,7 @@ export class ZonDecoder {
                 // Handle implicit array item starting with dash in value?
                 // No, _parseZonNode handles that recursively.
 
-                const key = this._parseValue(keyStr);
+                const key = this._parseKey(keyStr);
                 const val = this._parseZonNode(valStr, depth + 1);
                 obj[key] = val;
              }
@@ -823,7 +823,7 @@ export class ZonDecoder {
                 const colonIdx = this._findDelimiter(item, ':');
                 const keyStr = item.substring(0, colonIdx).trim();
                 const valStr = item.substring(colonIdx + 1).trim();
-                const key = this._parseValue(keyStr);
+                const key = this._parseKey(keyStr);
                 const val = this._parseZonNode(valStr, depth + 1);
                 obj[key] = val;
              }
@@ -856,7 +856,7 @@ export class ZonDecoder {
                    const colonIdx = this._findDelimiter(line.trim(), ':');
                    const keyStr = line.substring(0, colonIdx).trim();
                    const valStr = line.substring(colonIdx + 1).trim();
-                   const key = this._parseValue(keyStr);
+                   const key = this._parseKey(keyStr);
                    const val = this._parseZonNode(valStr, depth + 1);
                    obj[key] = val;
                 }
@@ -1043,6 +1043,10 @@ export class ZonDecoder {
     return parsed;
   }
 
+  private _parseKey(val: string): string {
+    return parseKey(val);
+  }
+
 
 
   /**

src/core/encoder.ts

@@ -449,7 +449,9 @@ export class ZonEncoder {
     const lines: string[] = [];
 
     for (const [col, values] of dictionaries) {
-      lines.push(`${col}[${values.length}]:${values.join(',')}`);
+      // Quote dictionary values that contain special characters
+      const formattedValues = values.map(v => this._formatValue(v));
+      lines.push(`${col}[${values.length}]:${formattedValues.join(',')}`);
     }
 
     const dictCols = Array.from(dictionaries.keys());
@@ -628,7 +630,8 @@ export class ZonEncoder {
       const items: string[] = [];
       for (const k of keys) {
         let kStr = String(k);
-        if (/[,:\{\}\[\]"]/.test(kStr)) {
+        // Quote keys with special chars OR boolean/null keywords
+        if (/[,:\{\}\[\]"]/.test(kStr) || /^(true|false|t|f|null|none|nil)$/i.test(kStr)) {
           kStr = JSON.stringify(kStr);
         }
 

src/core/utils.ts

@@ -21,6 +21,41 @@ export function quoteString(s: string): string {
   return `"${zon}"`;
 }
 
+/**
+ * Parses a ZON dictionary key string.
+ *
+ * Unlike parseValue, this does NOT convert boolean keywords (t, f, true, false)
+ * or null keywords to their typed equivalents. Keys are always strings.
+ *
+ * @param val - The key string to parse
+ * @returns The parsed key as a string
+ */
+export function parseKey(val: string): string {
+  const trimmed = val.trim();
+
+  if (trimmed.startsWith('"')) {
+    try {
+      return JSON.parse(trimmed);
+    } catch {
+      if (trimmed.endsWith('"')) {
+        const inner = trimmed.slice(1, -1);
+        const fixed = inner.replace(/""/g, '\\"');
+        try {
+          return JSON.parse(`"${fixed}"`);
+        } catch {
+          return trimmed.slice(1, -1).replace(/""/g, '"');
+        }
+      }
+    }
+  }
+
+  if (trimmed.startsWith("'") && trimmed.endsWith("'")) {
+    return trimmed.slice(1, -1);
+  }
+
+  return trimmed;
+}
+
 /**
  * Parses a ZON value string into its corresponding primitive type.
  * Handles booleans, nulls, numbers, arrays, objects, and quoted strings.