From bfc6df303e90a9f84740baa71960f466983b2821 Mon Sep 17 00:00:00 2001
From: Ian Wahbe <ian@wahbe.com>
Date: Mon, 8 Nov 2021 18:13:05 -0800
Subject: [PATCH] Experiment with parsing json

---
 pkg/go.mod                    |   1 +
 pkg/go.sum                    |   3 +
 pkg/util/parsing/json.go      | 116 ++++++++++++++++++++++++++++++++++
 pkg/util/parsing/json_test.go |  11 ++++
 4 files changed, 131 insertions(+)
 create mode 100644 pkg/util/parsing/json.go
 create mode 100644 pkg/util/parsing/json_test.go

diff --git a/pkg/go.mod b/pkg/go.mod
index f7c215450..9ee9cc3e2 100644
--- a/pkg/go.mod
+++ b/pkg/go.mod
@@ -84,6 +84,7 @@ require (
 	github.com/Azure/go-autorest/logger v0.2.1 // indirect
 	github.com/Azure/go-autorest/tracing v0.6.0 // indirect
 	github.com/agext/levenshtein v1.2.1 // indirect
+	github.com/alecthomas/participle/v2 v2.0.0-alpha7 // indirect
 	github.com/apparentlymart/go-textseg v1.0.0 // indirect
 	github.com/cheggaaa/pb v1.0.18 // indirect
 	github.com/cpuguy83/go-md2man/v2 v2.0.0 // indirect
diff --git a/pkg/go.sum b/pkg/go.sum
index d1ace4103..33eb3e7c1 100644
--- a/pkg/go.sum
+++ b/pkg/go.sum
@@ -112,6 +112,9 @@ github.com/agext/levenshtein v1.2.1 h1:QmvMAjj2aEICytGiWzmxoE0x2KZvE0fvmqMOfy2tj
 github.com/agext/levenshtein v1.2.1/go.mod h1:JEDfjyjHDjOF/1e4FlBE/PkbqA9OfWu2ki2W0IB5558=
 github.com/alcortesm/tgz v0.0.0-20161220082320-9c5fe88206d7 h1:uSoVVbwJiQipAclBbw+8quDsfcvFjOpI5iCf4p/cqCs=
 github.com/alcortesm/tgz v0.0.0-20161220082320-9c5fe88206d7/go.mod h1:6zEj6s6u/ghQa61ZWa/C2Aw3RkjiTBOix7dkqa1VLIs=
+github.com/alecthomas/participle/v2 v2.0.0-alpha7 h1:cK4vjj0VSgb3lN1nuKA5F7dw+1s1pWBe5bx7nNCnN+c=
+github.com/alecthomas/participle/v2 v2.0.0-alpha7/go.mod h1:NumScqsC42o9x+dGj8/YqsIfhrIQjFEOFovxotbBirA=
+github.com/alecthomas/repr v0.0.0-20181024024818-d37bc2a10ba1/go.mod h1:xTS7Pm1pD1mvyM075QCDSRqH6qRLXylzS24ZTpRiSzQ=
 github.com/alecthomas/template v0.0.0-20160405071501-a0175ee3bccc/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
 github.com/alecthomas/template v0.0.0-20190718012654-fb15b899a751/go.mod h1:LOuyumcjzFXgccqObfd/Ljyb9UuFJ6TxHnclSeseNhc=
 github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
diff --git a/pkg/util/parsing/json.go b/pkg/util/parsing/json.go
new file mode 100644
index 000000000..303e7745a
--- /dev/null
+++ b/pkg/util/parsing/json.go
@@ -0,0 +1,116 @@
+package parsing
+
+import (
+	"fmt"
+
+	"github.com/alecthomas/participle/v2"
+	"github.com/alecthomas/participle/v2/lexer"
+)
+
+type Value struct {
+	Object  *Object `  @@`
+	Array   *Array  `| @@`
+	String_ *string `| @String`
+	Number  *Number `| @@`
+	Null    *bool   `| "null"`
+	Bool    *bool   `| (@"true" | "false")`
+}
+
+func (v *Value) String() string {
+	switch {
+	case v.Object != nil:
+		return v.Object.String()
+	case v.Array != nil:
+		return v.Array.String()
+	case v.String_ != nil:
+		return *v.String_
+	case v.Number != nil:
+		return v.Number.String()
+	case v.Null != nil:
+		return "null"
+	case v.Bool != nil:
+		if *v.Bool {
+			return "true"
+		}
+		return "false"
+	default:
+		panic("Value not initialized")
+	}
+}
+
+type Object struct {
+	Members []*Member `"{" ( @@ ( "," @@ )* )? "}"`
+}
+
+func (o *Object) String() string {
+	if len(o.Members) == 0 {
+		return "{ }"
+	}
+	s := "{ " + o.Members[0].String()
+	for i := 1; i < len(o.Members); i++ {
+		s = s + ", " + o.Members[i].String()
+	}
+	return s + " }"
+}
+
+type Member struct {
+	Key   *string `@String ":"`
+	Value *Value  `@@`
+}
+
+func (m Member) String() string {
+	return *m.Key + ": " + (*m.Value).String()
+}
+
+type Array struct {
+	Entries []*Value `"[" ( @@ ( "," @@ )* )? "]"`
+}
+
+func (a Array) String() string {
+	if len(a.Entries) == 0 {
+		return "[ ]"
+	}
+	s := "[ " + a.Entries[0].String()
+	for i := 1; i < len(a.Entries); i++ {
+		s = s + ", " + a.Entries[i].String()
+	}
+	return s + " ]"
+}
+
+type Number struct {
+	Integer  *Integer  `@@`
+	Fraction *Fraction `@@`
+	Exponent *Exponent `@@`
+}
+
+type Integer struct {
+	Minus *char   `@"-"`
+	digit *string `@Digit`
+	rest  *string `@OneNine`
+}
+
+func (n Number) String() string {
+	return *n.Integer
+}
+
+func ParseJSON(s string) {
+	jsonLexer := lexer.Must(lexer.NewSimple([]lexer.Rule{
+		{"Digit", `[0-9]`, nil},
+		{"OneNine", `[1-9]`, nil},
+		{"whitespace", `\s+`, nil},
+		{"String", `"[^"]*"`, nil},
+		{"Punct", `[\{\}\[\],:]`, nil},
+		{"Null", "null", nil},
+		{"Bool", "true|false", nil},
+	}))
+
+	jsonParser := participle.MustBuild(&Value{}, participle.Lexer(jsonLexer), participle.Unquote("String"))
+
+	json := &Value{}
+	err := jsonParser.ParseString("schema", s, json)
+	if err != nil {
+		fmt.Println(err.Error())
+	} else {
+		fmt.Printf("JSON parsed to %v\n", json)
+	}
+}
diff --git a/pkg/util/parsing/json_test.go b/pkg/util/parsing/json_test.go
new file mode 100644
index 000000000..24c187737
--- /dev/null
+++ b/pkg/util/parsing/json_test.go
@@ -0,0 +1,11 @@
+package parsing
+
+import (
+	"testing"
+)
+
+func TestJsonParsing(t *testing.T) {
+	s := `{ "jo" : 89, "phinues": "pherb"}`
+	ParseJSON(s)
+	t.FailNow()
+}