mirror of
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107 lines
3.8 KiB
Markdown
107 lines
3.8 KiB
Markdown
# Iris Path Expression Language (_future)
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## Ideas & Goals
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- Optional.
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- No Breaking Changes.
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- No performance cost if not used.
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- Can convert a path for the existing routers, if no router is being used, then it will use its own, new, router.
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- 4+1 basic parameter types: `int`, `string`, `alphabetical`, `path`, (wildcard), `any` based on regexp.
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- Each type has unlimited functions of its own, they should be able to be overriden.
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- Give devs the ability to parse their function's arguments before use them and return a func which is the validator.
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- Function will be a generic type(`interface{}`) in order to devs be able to use any type without boilerplate code for conversions,
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can be done using reflection and reflect.Call, on .Boot time to parse the function automatically, and keep the returning validator function (already tested and worked).
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- The `any` will be the default if dev use functions to the named path parameter but missing a type.
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- If a type doesnt't contains a function of its own, then it will use the `any`'s, so `any` will contain global-use functions too.
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## Preview
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`/api/users/{id:int min(1)}/posts`
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```go
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minValidator := func(min int) func(string) bool {
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return func(paramValue string) bool {
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paramValueInt, err := strconv.Atoi(paramValue)
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if err != nil {
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return false
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}
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if paramValueInt < min {
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return false
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}
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return true
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}
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}
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app := iris.New()
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app.Int.Set("min", minValidator)
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```
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`/api/{version:string len(2) isVersion()}`
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```go
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isVersionStrValidator := func() func(string) bool {
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versions := []string("v1","v2")
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return func(paramValue string) bool {
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for _, s := range versions {
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if s == paramValue {
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return true
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}
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}
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return false
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}
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}
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lenStrValidator := func(i int) func(string) bool {
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if i <= 0 {
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i = 1
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}
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return func(paramValue string) bool {
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return len(paramValue) != i
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}
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}
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app := iris.New()
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app.String.Set("isVersion", isVersionStrValidator)
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app.String.Set("len", lenStrValidator)
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```
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`/uploads/{filepath:tail contains(.) else 403}`
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```go
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[...]
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[...]
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```
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`/api/validate/year/{year:int range(1970,2017) else 500}`
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```go
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[...]
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[...]
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```
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## Resources
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- [Lexical analysis](https://en.wikipedia.org/wiki/Lexical_analysis) **necessary**
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- [Top-down parsing](https://en.wikipedia.org/wiki/Top-down_parsing) **necessary**
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- [Recursive descent parser](https://en.wikipedia.org/wiki/Recursive_descent_parser) **basic, continue to the rest after**
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- [Handwritten Parsers & Lexers in Go](https://blog.gopheracademy.com/advent-2014/parsers-lexers/) **very good**
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- [Creating a VM / Compiler Episode 1: Bytecode VM](https://www.youtube.com/watch?v=DUNkdl0Jhgs) **nice to watch**
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- [So you want to write an interpreter?](https://www.youtube.com/watch?v=LCslqgM48D4) **watch it, continue to the rest later on**
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- [Writing a Lexer and Parser in Go - Part 1](http://adampresley.github.io/2015/04/12/writing-a-lexer-and-parser-in-go-part-1.html) **a different approach using the strategy pattern, not for production use in my opinion**
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- [Writing a Lexer and Parser in Go - Part 2](http://adampresley.github.io/2015/05/12/writing-a-lexer-and-parser-in-go-part-2.html)
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- [Writing a Lexer and Parser in Go - Part 3](http://adampresley.github.io/2015/06/01/writing-a-lexer-and-parser-in-go-part-3.html)
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- [Writing An Interpreter In Go](https://www.amazon.com/Writing-Interpreter-Go-Thorsten-Ball/dp/300055808X) **I recommend this book: suitable for both experienced and novice developers**
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<!-- author's notes:
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When finish, I should write an article for new Gophers, based on all of that I have read the last months on this subject.
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It will help a lot new developers looking for these things.
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Also, don't push commits to the _future folder for each change, commit every 2-3 days is enough.
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-->
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