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fix: conditional type generation #30

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Merged
alexander-akait merged 2 commits into from
Feb 15, 2026
Merged

fix: conditional type generation #30

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a7c19c3
fix: conditional type generation
alexander-akait Feb 15, 2026
1a874cb
style: fix
alexander-akait Feb 15, 2026
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139 changes: 131 additions & 8 deletions generate-types/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -540,8 +540,9 @@ const printError = (diagnostic) => {
/** @typedef {{ type: "index", symbolName: SymbolName, objectType: ts.Type, indexType: ts.Type }} ParsedIndexType */
/** @typedef {{ type: "template", texts: readonly string[], types: readonly ts.Type[] }} ParsedTemplateType */
/** @typedef {{ type: "import", symbolName: SymbolName, exportName: string, from: string, isValue: boolean }} ParsedImportType */
/** @typedef {{ type: "symbol", symbolName: SymbolName }} ParsedSymbolType */
/** @typedef {ParsedPrimitiveType | ParsedTypeParameterType | ParsedTupleType | ParsedInterfaceType | ParsedReferenceType | ParsedUnionType | ParsedIntersectionType | ParsedIndexType | ParsedTemplateType | ParsedImportType | ParsedSymbolType} ParsedType */
/** @typedef {{ type: "symbol", symbolName: SymbolName}} ParsedSymbolType */
/** @typedef {{ type: "conditional", symbolName: SymbolName, checkType: ts.Type, extendsType: ts.Type, trueType: ts.Type, falseType: ts.Type, typeParameters?: readonly ts.Type[] }} ParsedConditionalType */
/** @typedef {ParsedPrimitiveType | ParsedTypeParameterType | ParsedTupleType | ParsedInterfaceType | ParsedReferenceType | ParsedUnionType | ParsedIntersectionType | ParsedIndexType | ParsedTemplateType | ParsedImportType | ParsedSymbolType | ParsedConditionalType} ParsedType */
/** @typedef {ParsedType | MergedClassType | MergedNamespaceType} MergedType */

const isExcluded = (name) => {
Expand Down Expand Up @@ -848,6 +849,8 @@ const printError = (diagnostic) => {
return argsWithoutDefaults;
};

const symbol = type.aliasSymbol || type.getSymbol();

if (/** @type {any} */ (type).isTypeParameter()) {
return {
type: "typeParameter",
Expand Down Expand Up @@ -1053,8 +1056,6 @@ const printError = (diagnostic) => {
};
}

const symbol = type.aliasSymbol || type.getSymbol();

if (objectFlags & ts.ObjectFlags.Reference) {
const typeRef = /** @type {ts.TypeReference} */ (type);
const typeArguments = checker.getTypeArguments(typeRef);
Expand Down Expand Up @@ -1200,6 +1201,38 @@ const printError = (diagnostic) => {
};
}

if (flags & ts.TypeFlags.Conditional) {
const { checkType, extendsType, root } =
/** @type {ts.ConditionalType} */ (type);

return {
type: "conditional",
symbolName,
checkType,
extendsType,
trueType: checker.getTypeAtLocation(root.node.trueType),
falseType: checker.getTypeAtLocation(root.node.falseType),
typeParameters:
type.aliasTypeArguments && type.aliasTypeArguments.length > 0
? type.aliasTypeArguments
: undefined,
// skip: true,
};
}

if (flags & ts.TypeFlags.IndexedAccess) {
const { objectType, indexType } = /** @type {ts.IndexedAccessType} */ (
type
);

return {
type: "index",
symbolName: parseName(type),
objectType,
indexType,
};
}

const declaration = getDeclaration(symbol);

return {
Expand Down Expand Up @@ -1289,6 +1322,12 @@ const printError = (diagnostic) => {
captureType(type, inner);
}
break;
case "conditional":
captureType(type, parsed.checkType);
captureType(type, parsed.extendsType);
captureType(type, parsed.trueType);
captureType(type, parsed.falseType);
break;
case "interface":
for (const prop of parsed.baseTypes) {
typeUsedAsBaseType.add(prop);
Expand Down Expand Up @@ -1651,6 +1690,18 @@ const printError = (diagnostic) => {
return x === undefined ? item : x;
});
}
case "conditional": {
const { symbolName, checkType, extendsType, trueType, falseType } =
parsed;
return [
parsed.type,
symbolName[0],
checkType,
extendsType,
trueType,
falseType,
];
}
case "interface": {
const {
symbolName,
Expand Down Expand Up @@ -1770,6 +1821,12 @@ const printError = (diagnostic) => {
const needName = [];
for (const [type, parsed] of parsedCollectedTypes) {
switch (parsed.type) {
case "conditional": {
if (parsed.typeParameters) {
needName.push([type, parsed]);
}
break;
}
case "interface": {
if (
parsed.typeParameters ||
Expand Down Expand Up @@ -2157,6 +2214,7 @@ const printError = (diagnostic) => {
return parsed.name;
case "typeParameter": {
let code = parsed.name;

if (state === "in type args") {
if (parsed.constraint) {
const constraint = getCode(parsed.constraint, typeArgs, state);
Expand All @@ -2167,6 +2225,7 @@ const printError = (diagnostic) => {
code += ` = ${defaultValue}`;
}
}

return code;
}
case "template": {
Expand All @@ -2180,10 +2239,21 @@ const printError = (diagnostic) => {
return code;
}
case "index": {
return `(${getCode(parsed.objectType, typeArgs)})[${getCode(
parsed.indexType,
typeArgs,
)}]`;
const { objectType, indexType } = parsed;
const getIndexTypeCode = () => {
if (indexType.flags & ts.TypeFlags.Substitution) {
const { baseType } = /** @type {ts.SubstitutionType} */ (indexType);
const symbol = baseType.getSymbol();
if (symbol) {
const name = symbol.getName();
if (name !== "__type" && name !== "unknown") return name;
}
}

return getCode(indexType, typeArgs);
};

return `(${getCode(objectType, typeArgs)})[${getIndexTypeCode()}]`;
}
case "union":
case "intersection": {
Expand Down Expand Up @@ -2261,6 +2331,59 @@ const printError = (diagnostic) => {
"with type args",
)}${typeArgumentsWithoutDefaults}`;
}
case "conditional": {
const getExtendsString = (t) => {
if (t.flags & ts.TypeFlags.TypeParameter) {
const symbol = t.getSymbol();
if (
symbol &&
symbol.declarations &&
symbol.declarations.length > 0
) {
const decl = symbol.declarations[0];
if (
ts.isTypeParameterDeclaration(decl) &&
decl.parent &&
ts.isInferTypeNode(decl.parent)
) {
return "infer " + symbol.getName();
}
}
return symbol ? symbol.getName() : getCode(t, typeArgs, state);
}

if (checker.isArrayType(t)) {
const elementType = t.typeArguments[0];
return "(" + getExtendsString(elementType) + ")[]";
}

return getCode(t, typeArgs, state);
};

const checkType = getCode(parsed.checkType, typeArgs, state);
const extendsType = getExtendsString(parsed.extendsType);
const trueType = getCode(parsed.trueType, typeArgs, state);
const falseType = getCode(parsed.falseType, typeArgs, state);

const variable = typeToVariable.get(type);
if (variable !== undefined) {
queueDeclaration(
type,
variable,
() =>
`type ${variable}${
parsed.typeParameters
? `<${parsed.typeParameters
.map((t) => getCode(t, new Set(), "in type args"))
.join(", ")}>`
: ""
} = (${checkType} extends ${extendsType} ? ${trueType} : ${falseType});`,
);
return `${variable}`;
}

return `(${checkType} extends ${extendsType} ? ${trueType} : ${falseType})`;
}
case "interface": {
const variable = typeToVariable.get(type);
if (variable !== undefined) {
Expand Down