🧠 Logic: 🧱 implement json_prolog/2

Dockerfile

@@ -9,7 +9,7 @@ ADD https://github.com/CosmWasm/wasmvm/releases/download/v1.2.1/libwasmvm_muslc.
 
 # hadolint ignore=DL4006
 RUN set -eux \
-    && apk add --no-cache ca-certificates=20220614-r0 build-base=0.5-r3 git=2.36.5-r0 linux-headers=5.16.7-r1 \
+    && apk add --no-cache ca-certificates=20220614-r0 build-base=0.5-r3 git=2.36.6-r0 linux-headers=5.16.7-r1 \
     && sha256sum /lib/libwasmvm_muslc.aarch64.a | grep 86bc5fdc0f01201481c36e17cd3dfed6e9650d22e1c5c8983a5b78c231789ee0 \
     && sha256sum /lib/libwasmvm_muslc.x86_64.a | grep a00700aa19f5bfe0f46290ddf69bf51eb03a6dfcd88b905e1081af2e42dbbafc \
     && cp "/lib/libwasmvm_muslc.$(uname -m).a" /lib/libwasmvm_muslc.a

x/logic/interpreter/registry.go

@@ -111,6 +111,7 @@ var registry = map[string]any{
 	"hex_bytes/2":               predicate.HexBytes,
 	"bech32_address/2":          predicate.Bech32Address,
 	"source_file/1":             predicate.SourceFile,
+	"json_prolog/2":             predicate.JSONProlog,
 }
 
 // RegistryNames is the list of the predicate names in the Registry.

x/logic/predicate/json.go

@@ -0,0 +1,182 @@
+package predicate
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"sort"
+	"strings"
+
+	"cosmossdk.io/math"
+	sdk "github.com/cosmos/cosmos-sdk/types"
+	"github.com/ichiban/prolog/engine"
+	"github.com/okp4/okp4d/x/logic/util"
+	"github.com/samber/lo"
+)
+
+// AtomJSON is a term which represents a json as a compound term `json([Pair])`.
+var AtomJSON = engine.NewAtom("json")
+
+// JSONProlog is a predicate that will unify a JSON string into prolog terms and vice versa.
+//
+// json_prolog(?Json, ?Term) is det
+//
+// Where
+//   - `Json` is the string representation of the json
+//   - `Term` is an Atom that would be unified by the JSON representation as Prolog terms.
+//
+// In addition, when passing Json and Term, this predicate return true if both result match.
+//
+// Example:
+//
+// # JSON conversion to Prolog.
+// - json_prolog('{"foo": "bar"}', json([foo-bar])).
+func JSONProlog(vm *engine.VM, j, term engine.Term, cont engine.Cont, env *engine.Env) *engine.Promise {
+	return engine.Delay(func(ctx context.Context) *engine.Promise {
+		var result engine.Term
+
+		switch t1 := env.Resolve(j).(type) {
+		case engine.Variable:
+		case engine.Atom:
+			terms, err := jsonStringToTerms(t1.String())
+			if err != nil {
+				return engine.Error(fmt.Errorf("json_prolog/2: %w", err))
+			}
+			result = terms
+		default:
+			return engine.Error(fmt.Errorf("json_prolog/2: cannot unify json with %T", t1))
+		}
+
+		switch t2 := env.Resolve(term).(type) {
+		case engine.Variable:
+			if result == nil {
+				return engine.Error(fmt.Errorf("json_prolog/2: could not unify two variable"))
+			}
+			return engine.Unify(vm, term, result, cont, env)
+		default:
+			b, err := termsToJSON(t2, env)
+			if err != nil {
+				return engine.Error(fmt.Errorf("json_prolog/2: %w", err))
+			}
+
+			b, err = sdk.SortJSON(b)
+			if err != nil {
+				return engine.Error(fmt.Errorf("json_prolog/2: %w", err))
+			}
+			return engine.Unify(vm, j, util.StringToTerm(string(b)), cont, env)
+		}
+	})
+}
+
+func jsonStringToTerms(j string) (engine.Term, error) {
+	var values any
+	decoder := json.NewDecoder(strings.NewReader(j))
+	decoder.UseNumber() // unmarshal a number into an interface{} as a Number instead of as a float64
+
+	if err := decoder.Decode(&values); err != nil {
+		return nil, err
+	}
+
+	return jsonToTerms(values)
+}
+
+func termsToJSON(term engine.Term, env *engine.Env) ([]byte, error) {
+	switch t := term.(type) {
+	case engine.Atom:
+		return json.Marshal(t.String())
+	case engine.Integer:
+		return json.Marshal(t)
+	case engine.Compound:
+		switch t.Functor().String() {
+		case ".": // Represent an engine.List
+			if t.Arity() != 2 {
+				return nil, fmt.Errorf("wrong term arity for array, give %d, expected %d", t.Arity(), 2)
+			}
+
+			iter := engine.ListIterator{List: t, Env: env}
+
+			elements := make([]json.RawMessage, 0)
+			for iter.Next() {
+				element, err := termsToJSON(env.Resolve(iter.Current()), env)
+				if err != nil {
+					return nil, err
+				}
+				elements = append(elements, element)
+			}
+			return json.Marshal(elements)
+		case AtomJSON.String():
+			terms, err := ExtractJSONTerm(t, env)
+			if err != nil {
+				return nil, err
+			}
+
+			attributes := make(map[string]json.RawMessage, len(terms))
+			for key, term := range terms {
+				raw, err := termsToJSON(env.Resolve(term), env)
+				if err != nil {
+					return nil, err
+				}
+				attributes[key] = raw
+			}
+			return json.Marshal(attributes)
+		}
+
+		switch {
+		case AtomBool(true).Compare(t, env) == 0:
+			return json.Marshal(true)
+		case AtomBool(false).Compare(t, env) == 0:
+			return json.Marshal(false)
+		case AtomNull.Compare(t, env) == 0:
+			return json.Marshal(nil)
+		}
+
+		return nil, fmt.Errorf("invalid functor %s", t.Functor())
+	default:
+		return nil, fmt.Errorf("could not convert %s {%T} to json", t, t)
+	}
+}
+
+func jsonToTerms(value any) (engine.Term, error) {
+	switch v := value.(type) {
+	case string:
+		return util.StringToTerm(v), nil
+	case json.Number:
+		r, ok := math.NewIntFromString(string(v))
+		if !ok {
+			return nil, fmt.Errorf("could not convert number '%s' into integer term, decimal number is not handled yet", v)
+		}
+		if !r.IsInt64() {
+			return nil, fmt.Errorf("could not convert number '%s' into integer term, overflow", v)
+		}
+		return engine.Integer(r.Int64()), nil
+	case bool:
+		return AtomBool(v), nil
+	case nil:
+		return AtomNull, nil
+	case map[string]any:
+		keys := lo.Keys(v)
+		sort.Strings(keys)
+
+		attributes := make([]engine.Term, 0, len(v))
+		for _, key := range keys {
+			attributeValue, err := jsonToTerms(v[key])
+			if err != nil {
+				return nil, err
+			}
+			attributes = append(attributes, AtomPair.Apply(engine.NewAtom(key), attributeValue))
+		}
+		return AtomJSON.Apply(engine.List(attributes...)), nil
+	case []any:
+		elements := make([]engine.Term, 0, len(v))
+		for _, element := range v {
+			term, err := jsonToTerms(element)
+			if err != nil {
+				return nil, err
+			}
+			elements = append(elements, term)
+		}
+		return engine.List(elements...), nil
+	default:
+		return nil, fmt.Errorf("could not convert %s (%T) to a prolog term", v, v)
+	}
+}