func findDeclsAndUnresolved()

in internal/godoc/internal/doc/example.go [304:439]
110 lines of code
37 McCabe index (conditional complexity)

func findDeclsAndUnresolved(body ast.Node, topDecls map[*ast.Object]ast.Decl, typMethods map[string][]ast.Decl) ([]ast.Decl, map[string]bool) {
	var depDecls []ast.Decl
	unresolved := make(map[string]bool)
	hasDepDecls := make(map[ast.Decl]bool)
	objs := map[*ast.Object]bool{}

	var inspectFunc func(ast.Node) bool
	inspectFunc = func(n ast.Node) bool {
		switch e := n.(type) {
		case *ast.Ident:
			if e.Obj == nil && e.Name != "_" {
				unresolved[e.Name] = true
			} else if d := topDecls[e.Obj]; d != nil {
				objs[e.Obj] = true
				if !hasDepDecls[d] {
					hasDepDecls[d] = true
					depDecls = append(depDecls, d)
				}
			}
			return true
		case *ast.SelectorExpr:
			// For selector expressions, only inspect the left hand side.
			// (For an expression like fmt.Println, only add "fmt" to the
			// set of unresolved names, not "Println".)
			ast.Inspect(e.X, inspectFunc)
			return false
		case *ast.KeyValueExpr:
			// For key value expressions, only inspect the value
			// as the key should be resolved by the type of the
			// composite literal.
			ast.Inspect(e.Value, inspectFunc)
			return false
		}
		return true
	}
	ast.Inspect(body, inspectFunc)
	for i := 0; i < len(depDecls); i++ {
		switch d := depDecls[i].(type) {
		case *ast.FuncDecl:
			// Inspect types of parameters and results. See #28492.
			if d.Type.Params != nil {
				for _, p := range d.Type.Params.List {
					ast.Inspect(p.Type, inspectFunc)
				}
			}
			if d.Type.Results != nil {
				for _, r := range d.Type.Results.List {
					ast.Inspect(r.Type, inspectFunc)
				}
			}

			ast.Inspect(d.Body, inspectFunc)
		case *ast.GenDecl:
			for _, spec := range d.Specs {
				switch s := spec.(type) {
				case *ast.TypeSpec:
					ast.Inspect(s.Type, inspectFunc)
					depDecls = append(depDecls, typMethods[s.Name.Name]...)
				case *ast.ValueSpec:
					if s.Type != nil {
						ast.Inspect(s.Type, inspectFunc)
					}
					for _, val := range s.Values {
						ast.Inspect(val, inspectFunc)
					}
				}
			}
		}
	}
	// Some decls include multiple specs, such as a variable declaration with
	// multiple variables on the same line, or a parenthesized declaration. Trim
	// the declarations to include only the specs that are actually mentioned.
	// However, if there is a constant group with iota, leave it all: later
	// constant declarations in the group may have no value and so cannot stand
	// on their own, and furthermore, removing any constant from the group could
	// change the values of subsequent ones.
	// See testdata/examples/iota.go for a minimal example.
	ds := depDecls[:0]
	for _, d := range depDecls {
		switch d := d.(type) {
		case *ast.FuncDecl:
			ds = append(ds, d)
		case *ast.GenDecl:
			// Collect all Specs that were mentioned in the example.
			var specs []ast.Spec
			for _, s := range d.Specs {
				switch s := s.(type) {
				case *ast.TypeSpec:
					if objs[s.Name.Obj] {
						specs = append(specs, s)
					}
				case *ast.ValueSpec:
					// A ValueSpec may have multiple names (e.g. "var a, b int").
					// Keep only the names that were mentioned in the example.
					// Exception: the multiple names have a single initializer (which
					// would be a function call with multiple return values). In that
					// case, keep everything.
					if len(s.Names) > 1 && len(s.Values) == 1 {
						specs = append(specs, s)
						continue
					}
					ns := *s
					ns.Names = nil
					ns.Values = nil
					for i, n := range s.Names {
						if objs[n.Obj] {
							ns.Names = append(ns.Names, n)
							if s.Values != nil {
								ns.Values = append(ns.Values, s.Values[i])
							}
						}
					}
					if len(ns.Names) > 0 {
						specs = append(specs, &ns)
					}
				}
			}
			if len(specs) > 0 {
				// Constant with iota? Keep it all.
				if d.Tok == token.CONST && hasIota(d.Specs[0]) {
					ds = append(ds, d)
				} else {
					// Synthesize a GenDecl with just the Specs we need.
					nd := *d // copy the GenDecl
					nd.Specs = specs
					if len(specs) == 1 {
						// Remove grouping parens if there is only one spec.
						nd.Lparen = 0
					}
					ds = append(ds, &nd)
				}
			}
		}
	}
	return ds, unresolved
}