function isStableKnownHookValue()

in packages/eslint-plugin-react-hooks/src/ExhaustiveDeps.js [161:273]
94 lines of code
37 McCabe index (conditional complexity)

      function isStableKnownHookValue(resolved) {
        if (!isArray(resolved.defs)) {
          return false;
        }
        const def = resolved.defs[0];
        if (def == null) {
          return false;
        }
        // Look for `let stuff = ...`
        if (def.node.type !== 'VariableDeclarator') {
          return false;
        }
        let init = def.node.init;
        if (init == null) {
          return false;
        }
        while (init.type === 'TSAsExpression') {
          init = init.expression;
        }
        // Detect primitive constants
        // const foo = 42
        let declaration = def.node.parent;
        if (declaration == null) {
          // This might happen if variable is declared after the callback.
          // In that case ESLint won't set up .parent refs.
          // So we'll set them up manually.
          fastFindReferenceWithParent(componentScope.block, def.node.id);
          declaration = def.node.parent;
          if (declaration == null) {
            return false;
          }
        }
        if (
          declaration.kind === 'const' &&
          init.type === 'Literal' &&
          (typeof init.value === 'string' ||
            typeof init.value === 'number' ||
            init.value === null)
        ) {
          // Definitely stable
          return true;
        }
        // Detect known Hook calls
        // const [_, setState] = useState()
        if (init.type !== 'CallExpression') {
          return false;
        }
        let callee = init.callee;
        // Step into `= React.something` initializer.
        if (
          callee.type === 'MemberExpression' &&
          callee.object.name === 'React' &&
          callee.property != null &&
          !callee.computed
        ) {
          callee = callee.property;
        }
        if (callee.type !== 'Identifier') {
          return false;
        }
        const id = def.node.id;
        const {name} = callee;
        if (name === 'useRef' && id.type === 'Identifier') {
          // useRef() return value is stable.
          return true;
        } else if (name === 'useState' || name === 'useReducer') {
          // Only consider second value in initializing tuple stable.
          if (
            id.type === 'ArrayPattern' &&
            id.elements.length === 2 &&
            isArray(resolved.identifiers)
          ) {
            // Is second tuple value the same reference we're checking?
            if (id.elements[1] === resolved.identifiers[0]) {
              if (name === 'useState') {
                const references = resolved.references;
                for (let i = 0; i < references.length; i++) {
                  setStateCallSites.set(
                    references[i].identifier,
                    id.elements[0],
                  );
                }
              }
              // Setter is stable.
              return true;
            } else if (id.elements[0] === resolved.identifiers[0]) {
              if (name === 'useState') {
                const references = resolved.references;
                for (let i = 0; i < references.length; i++) {
                  stateVariables.add(references[i].identifier);
                }
              }
              // State variable itself is dynamic.
              return false;
            }
          }
        } else if (name === 'useTransition') {
          // Only consider second value in initializing tuple stable.
          if (
            id.type === 'ArrayPattern' &&
            id.elements.length === 2 &&
            Array.isArray(resolved.identifiers)
          ) {
            // Is second tuple value the same reference we're checking?
            if (id.elements[1] === resolved.identifiers[0]) {
              // Setter is stable.
              return true;
            }
          }
        }
        // By default assume it's dynamic.
        return false;
      }