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func_parser.go
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func_parser.go
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package methodfunc
import (
"errors"
"fmt"
"reflect"
"strings"
"github.com/kataras/iris/context"
)
var posWords = map[int]string{
0: "",
1: "first",
2: "second",
3: "third",
4: "forth",
5: "five",
6: "sixth",
7: "seventh",
8: "eighth",
9: "ninth",
}
func genParamKey(argIdx int) string {
return "param" + posWords[argIdx] // paramfirst, paramsecond...
}
const (
paramTypeInt = "int"
paramTypeLong = "long"
paramTypeBoolean = "boolean"
paramTypeString = "string"
paramTypePath = "path"
)
var macroTypes = map[string]string{
"int": paramTypeInt,
"int64": paramTypeLong,
"bool": paramTypeBoolean,
"string": paramTypeString,
// there is "path" param type but it's being captured "on-air"
// "file" param type is not supported by the current implementation, yet
// but if someone ask for it I'll implement it, it's easy.
}
type funcParser struct {
info FuncInfo
lexer *lexer
}
func newFuncParser(info FuncInfo) *funcParser {
return &funcParser{
info: info,
lexer: newLexer(info.Trailing),
}
}
func (p *funcParser) parse() (*ast, error) {
a := new(ast)
funcArgPos := 0
for {
w := p.lexer.next()
if w == "" {
break
}
if w == tokenBy {
funcArgPos++ // starting with 1 because in typ.NumIn() the first is the struct receiver.
// No need for these:
// ByBy will act like /{param:type}/{param:type} as users expected
// if func input arguments are there, else act By like normal path /by.
//
// if p.lexer.peekPrev() == tokenBy || typ.NumIn() == 1 { // ByBy, then act this second By like a path
// a.relPath += "/" + strings.ToLower(w)
// continue
// }
if err := p.parsePathParam(a, w, funcArgPos); err != nil {
return nil, err
}
continue
}
a.relPath += "/" + strings.ToLower(w)
}
// This fixes a problem when developer misses to append the keyword `By`
// to the method function when input arguments are declared (for path parameters binding).
// We could just use it with `By` keyword but this is not a good practise
// because what happens if we will become naive and declare something like
// Get(id int) and GetBy(username string) or GetBy(id int) ? it's not working because of duplication of the path.
// Docs are clear about that but we are humans, they may do a mistake by accident but
// framework will not allow that.
// So the best thing we can do to help prevent those errors is by printing that message
// below to the developer.
// Note: it should be at the end of the words loop because a.dynamic may be true later on.
if numIn := p.info.Type.NumIn(); numIn > 1 && !a.dynamic {
return nil, fmt.Errorf("found %d input arguments but keyword 'By' is missing from '%s'",
// -1 because end-developer wants to know the actual input arguments, without the struct holder.
numIn-1, p.info.Name)
}
return a, nil
}
func (p *funcParser) parsePathParam(a *ast, w string, funcArgPos int) error {
typ := p.info.Type
if typ.NumIn() <= funcArgPos {
// old:
// return nil, errors.New("keyword 'By' found but length of input receivers are not match for " +
// p.info.Name)
// By found but input arguments are not there, so act like /by path without restricts.
a.relPath += "/" + strings.ToLower(w)
return nil
}
var (
paramKey = genParamKey(funcArgPos) // paramfirst, paramsecond...
paramType = paramTypeString // default string
)
// string, int...
goType := typ.In(funcArgPos).Name()
nextWord := p.lexer.peekNext()
if nextWord == tokenWildcard {
p.lexer.skip() // skip the Wildcard word.
paramType = paramTypePath
} else if pType, ok := macroTypes[goType]; ok {
// it's not wildcard, so check base on our available macro types.
paramType = pType
} else {
return errors.New("invalid syntax for " + p.info.Name)
}
a.paramKeys = append(a.paramKeys, paramKey)
a.paramTypes = append(a.paramTypes, paramType)
// /{paramfirst:path}, /{paramfirst:long}...
a.relPath += fmt.Sprintf("/{%s:%s}", paramKey, paramType)
a.dynamic = true
if nextWord == "" && typ.NumIn() > funcArgPos+1 {
// By is the latest word but func is expected
// more path parameters values, i.e:
// GetBy(name string, age int)
// The caller (parse) doesn't need to know
// about the incremental funcArgPos because
// it will not need it.
return p.parsePathParam(a, nextWord, funcArgPos+1)
}
return nil
}
type ast struct {
paramKeys []string // paramfirst, paramsecond... [0]
paramTypes []string // string, int, long, path... [0]
relPath string
dynamic bool // when paramKeys (and paramTypes, are equal) > 0
}
// moved to func_caller#buildMethodcall, it's bigger and with repeated code
// than this, below function but it's faster.
// func (a *ast) MethodCall(ctx context.Context, f reflect.Value) {
// if a.dynamic {
// f.Call(a.paramValues(ctx))
// return
// }
//
// f.Interface().(func())()
// }
func (a *ast) paramValues(ctx context.Context) []reflect.Value {
if !a.dynamic {
return nil
}
l := len(a.paramKeys)
values := make([]reflect.Value, l, l)
for i := 0; i < l; i++ {
paramKey := a.paramKeys[i]
paramType := a.paramTypes[i]
values[i] = getParamValueFromType(ctx, paramType, paramKey)
}
return values
}
func getParamValueFromType(ctx context.Context, paramType string, paramKey string) reflect.Value {
if paramType == paramTypeInt {
v, _ := ctx.Params().GetInt(paramKey)
return reflect.ValueOf(v)
}
if paramType == paramTypeLong {
v, _ := ctx.Params().GetInt64(paramKey)
return reflect.ValueOf(v)
}
if paramType == paramTypeBoolean {
v, _ := ctx.Params().GetBool(paramKey)
return reflect.ValueOf(v)
}
// string, path...
return reflect.ValueOf(ctx.Params().Get(paramKey))
}