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macro.go
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macro.go
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package macro
import (
"fmt"
"reflect"
"regexp"
"strconv"
"unicode"
"github.com/kataras/iris/core/router/macro/interpreter/ast"
)
// EvaluatorFunc is the signature for both param types and param funcs.
// It should accepts the param's value as string
// and return true if validated otherwise false.
type EvaluatorFunc func(paramValue string) bool
// NewEvaluatorFromRegexp accepts a regexp "expr" expression
// and returns an EvaluatorFunc based on that regexp.
// the regexp is compiled before return.
//
// Returns a not-nil error on regexp compile failure.
func NewEvaluatorFromRegexp(expr string) (EvaluatorFunc, error) {
if expr == "" {
return nil, fmt.Errorf("empty regex expression")
}
// add the last $ if missing (and not wildcard(?))
if i := expr[len(expr)-1]; i != '$' && i != '*' {
expr += "$"
}
r, err := regexp.Compile(expr)
if err != nil {
return nil, err
}
return r.MatchString, nil
}
// MustNewEvaluatorFromRegexp same as NewEvaluatorFromRegexp
// but it panics on the "expr" parse failure.
func MustNewEvaluatorFromRegexp(expr string) EvaluatorFunc {
r, err := NewEvaluatorFromRegexp(expr)
if err != nil {
panic(err)
}
return r
}
var (
goodParamFuncReturnType = reflect.TypeOf(func(string) bool { return false })
goodParamFuncReturnType2 = reflect.TypeOf(EvaluatorFunc(func(string) bool { return false }))
)
func goodParamFunc(typ reflect.Type) bool {
// should be a func
// which returns a func(string) bool
if typ.Kind() == reflect.Func {
if typ.NumOut() == 1 {
typOut := typ.Out(0)
if typOut == goodParamFuncReturnType || typOut == goodParamFuncReturnType2 {
return true
}
}
}
return false
}
// goodParamFuncName reports whether the function name is a valid identifier.
func goodParamFuncName(name string) bool {
if name == "" {
return false
}
// valid names are only letters and _
for _, r := range name {
switch {
case r == '_':
case !unicode.IsLetter(r):
return false
}
}
return true
}
// the convertBuilderFunc return value is generating at boot time.
// convertFunc converts an interface to a valid full param function.
func convertBuilderFunc(fn interface{}) ParamEvaluatorBuilder {
typFn := reflect.TypeOf(fn)
if !goodParamFunc(typFn) {
return nil
}
numFields := typFn.NumIn()
return func(args []ast.ParamFuncArg) EvaluatorFunc {
if len(args) != numFields {
// no variadics support, for now.
panic("args should be the same len as numFields")
}
var argValues []reflect.Value
for i := 0; i < numFields; i++ {
field := typFn.In(i)
arg := args[i]
if field.Kind() != reflect.TypeOf(arg).Kind() {
panic("fields should have the same type")
}
argValues = append(argValues, reflect.ValueOf(arg))
}
evalFn := reflect.ValueOf(fn).Call(argValues)[0].Interface()
var evaluator EvaluatorFunc
// check for typed and not typed
if _v, ok := evalFn.(EvaluatorFunc); ok {
evaluator = _v
} else if _v, ok = evalFn.(func(string) bool); ok {
evaluator = _v
}
return func(paramValue string) bool {
return evaluator(paramValue)
}
}
}
type (
// Macro represents the parsed macro,
// which holds
// the evaluator (param type's evaluator + param functions evaluators)
// and its param functions.
//
// Any type contains its own macro
// instance, so an String type
// contains its type evaluator
// which is the "Evaluator" field
// and it can register param functions
// to that macro which maps to a parameter type.
Macro struct {
Evaluator EvaluatorFunc
funcs []ParamFunc
}
// ParamEvaluatorBuilder is a func
// which accepts a param function's arguments (values)
// and returns an EvaluatorFunc, its job
// is to make the macros to be registered
// by user at the most generic possible way.
ParamEvaluatorBuilder func([]ast.ParamFuncArg) EvaluatorFunc
// ParamFunc represents the parsed
// parameter function, it holds
// the parameter's name
// and the function which will build
// the evaluator func.
ParamFunc struct {
Name string
Func ParamEvaluatorBuilder
}
)
func newMacro(evaluator EvaluatorFunc) *Macro {
return &Macro{Evaluator: evaluator}
}
// RegisterFunc registers a parameter function
// to that macro.
// Accepts the func name ("range")
// and the function body, which should return an EvaluatorFunc
// a bool (it will be converted to EvaluatorFunc later on),
// i.e RegisterFunc("min", func(minValue int) func(paramValue string) bool){})
func (m *Macro) RegisterFunc(funcName string, fn interface{}) {
fullFn := convertBuilderFunc(fn)
m.registerFunc(funcName, fullFn)
}
func (m *Macro) registerFunc(funcName string, fullFn ParamEvaluatorBuilder) {
if !goodParamFuncName(funcName) {
return
}
for _, fn := range m.funcs {
if fn.Name == funcName {
fn.Func = fullFn
return
}
}
m.funcs = append(m.funcs, ParamFunc{
Name: funcName,
Func: fullFn,
})
}
func (m *Macro) getFunc(funcName string) ParamEvaluatorBuilder {
for _, fn := range m.funcs {
if fn.Name == funcName {
if fn.Func == nil {
continue
}
return fn.Func
}
}
return nil
}
// Map contains the default macros mapped to their types.
// This is the manager which is used by the caller to register custom
// parameter functions per param-type (String, Int, Long, Boolean, Alphabetical, File, Path).
type Map struct {
// string type
// anything
String *Macro
// uint type
// only positive numbers (+0-9)
// it could be uint/uint32 but we keep int for simplicity
Int *Macro
// long an int64 type
// only positive numbers (+0-9)
// it could be uint64 but we keep int64 for simplicity
Long *Macro
// boolean as bool type
// a string which is "1" or "t" or "T" or "TRUE" or "true" or "True"
// or "0" or "f" or "F" or "FALSE" or "false" or "False".
Boolean *Macro
// alphabetical/letter type
// letters only (upper or lowercase)
Alphabetical *Macro
// file type
// letters (upper or lowercase)
// numbers (0-9)
// underscore (_)
// dash (-)
// point (.)
// no spaces! or other character
File *Macro
// path type
// anything, should be the last part
Path *Macro
}
// NewMap returns a new macro Map with default
// type evaluators.
//
// Learn more at: https://github.com/kataras/iris/tree/master/_examples/routing/dynamic-path
func NewMap() *Map {
return &Map{
// it allows everything, so no need for a regexp here.
String: newMacro(func(string) bool { return true }),
Int: newMacro(MustNewEvaluatorFromRegexp("^[0-9]+$")),
Long: newMacro(MustNewEvaluatorFromRegexp("^[0-9]+$")),
Boolean: newMacro(func(paramValue string) bool {
// a simple if statement is faster than regex ^(true|false|True|False|t|0|f|FALSE|TRUE)$
// in this case.
_, err := strconv.ParseBool(paramValue)
return err == nil
}),
Alphabetical: newMacro(MustNewEvaluatorFromRegexp("^[a-zA-Z ]+$")),
File: newMacro(MustNewEvaluatorFromRegexp("^[a-zA-Z0-9_.-]*$")),
// it allows everything, we have String and Path as different
// types because I want to give the opportunity to the user
// to organise the macro functions based on wildcard or single dynamic named path parameter.
// Should be the last.
Path: newMacro(func(string) bool { return true }),
}
}
// Lookup returns the specific Macro from the map
// based on the parameter type.
// i.e if ast.ParamTypeInt then it will return the m.Int.
// Returns the m.String if not matched.
func (m *Map) Lookup(typ ast.ParamType) *Macro {
switch typ {
case ast.ParamTypeInt:
return m.Int
case ast.ParamTypeLong:
return m.Long
case ast.ParamTypeBoolean:
return m.Boolean
case ast.ParamTypeAlphabetical:
return m.Alphabetical
case ast.ParamTypeFile:
return m.File
case ast.ParamTypePath:
return m.Path
default:
return m.String
}
}