Find all functions that take an "error" as a parameter using Go's AST parser

find_functions_w_error_params.go

package main

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"log"
	"strings"
)


func main() {

	pkgRoot := "/Users/tleyden/Development/sync_gateway/godeps/src/github.com/couchbase/sync_gateway"

	processPackage(fmt.Sprintf("%s/auth", pkgRoot))
	processPackage(fmt.Sprintf("%s/base", pkgRoot))
	processPackage(fmt.Sprintf("%s/channels", pkgRoot))
	processPackage(fmt.Sprintf("%s/db", pkgRoot))
	processPackage(fmt.Sprintf("%s/rest", pkgRoot))

}

func processPackage(path string) {

	fset := token.NewFileSet()

	pkgs, err := parser.ParseDir(fset, path, nil, 0)
	if err != nil {
		panic(fmt.Sprintf("error parsing dir: %v", err))
	}
	for _, pkg := range pkgs {
		log.Printf("Processing package: %v", pkg.Name)
		for _, file := range pkg.Files {
			ast.Walk(new(FuncVisitor), file)
		}
	}

}

type FuncVisitor struct{}

func (v *FuncVisitor) Visit(node ast.Node) (w ast.Visitor) {

	switch t := node.(type) {
	case *ast.FuncDecl:
		t.Name = ast.NewIdent(strings.Title(t.Name.Name))
		for _, param := range t.Type.Params.List {
			argIdentifier, ok := param.Type.(*ast.Ident)
			if !ok {
				continue
			}
			if argIdentifier.Name == "error" {
				log.Printf("Function/method that takes an error type as a parameter: %v", t.Name)
			}
		}
	}

	return v
}