add IO::FS::READ function

go.sum

@@ -11,8 +11,8 @@ github.com/antchfx/htmlquery v1.1.0 h1:KMS88sLl5KP9GUVU2MQIDcQXNQ0M5MGlkC9WlYgAQ
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 github.com/antchfx/xpath v1.1.0 h1:mJTvYpiHvxNQRD4Lbfin/FodHVCHh2a5KrOFr4ZxMOI=
 github.com/antchfx/xpath v1.1.0/go.mod h1:Yee4kTMuNiPYJ7nSNorELQMr1J33uOpXDMByNYhvtNk=
-github.com/antlr/antlr4 v0.0.0-20190819145818-b43a4c3a8015 h1:StuiJFxQUsxSCzcby6NFZRdEhPkXD5vxN7TZ4MD6T84=
+github.com/antlr/antlr4 v0.0.0-20191005235324-c81b4e69b6c3 h1:bmbhqj60LNfApeR0sPmGCUXDm20s/gJ8EyYK9+hMe3k=
-github.com/antlr/antlr4 v0.0.0-20190819145818-b43a4c3a8015/go.mod h1:T7PbCXFs94rrTttyxjbyT5+/1V8T2TYDejxUfHJjw1Y=
+github.com/antlr/antlr4 v0.0.0-20191005235324-c81b4e69b6c3/go.mod h1:T7PbCXFs94rrTttyxjbyT5+/1V8T2TYDejxUfHJjw1Y=
 github.com/chzyer/logex v1.1.10 h1:Swpa1K6QvQznwJRcfTfQJmTE72DqScAa40E+fbHEXEE=
 github.com/chzyer/logex v1.1.10/go.mod h1:+Ywpsq7O8HXn0nuIou7OrIPyXbp3wmkHB+jjWRnGsAI=
 github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e h1:fY5BOSpyZCqRo5OhCuC+XN+r/bBCmeuuJtjz+bCNIf8=

pkg/stdlib/io/fs/lib.go

@@ -0,0 +1,15 @@
+package fs
+
+import (
+	"github.com/MontFerret/ferret/pkg/runtime/core"
+)
+
+// RegisterLib register `FS` namespace functions.
+func RegisterLib(ns core.Namespace) error {
+	return ns.
+		Namespace("FS").
+		RegisterFunctions(
+			core.NewFunctionsFromMap(map[string]core.Function{
+				"READ": Read,
+			}))
+}

pkg/stdlib/io/fs/read.go

@@ -0,0 +1,37 @@
+package fs
+
+import (
+	"context"
+	"io/ioutil"
+
+	"github.com/MontFerret/ferret/pkg/runtime/core"
+	"github.com/MontFerret/ferret/pkg/runtime/values"
+	"github.com/MontFerret/ferret/pkg/runtime/values/types"
+)
+
+// Read reads from a given file.
+// @params path (String) - path to file to read from.
+// @returns data (Binary) - the read file in binary format.
+func Read(_ context.Context, args ...core.Value) (core.Value, error) {
+	err := core.ValidateArgs(args, 1, 1)
+
+	if err != nil {
+		return values.None, core.Error(err, "validate arguments number")
+	}
+
+	err = core.ValidateType(args[0], types.String)
+
+	if err != nil {
+		return values.None, core.Error(err, "validate [0] argument")
+	}
+
+	path := args[0].String()
+
+	data, err := ioutil.ReadFile(path)
+
+	if err != nil {
+		return values.None, core.Error(err, "read file")
+	}
+
+	return values.NewBinary(data), nil
+}

pkg/stdlib/io/fs/read_test.go

@@ -0,0 +1,79 @@
+package fs_test
+
+import (
+	"context"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"github.com/MontFerret/ferret/pkg/runtime/core"
+	"github.com/MontFerret/ferret/pkg/runtime/values"
+	"github.com/MontFerret/ferret/pkg/runtime/values/types"
+	"github.com/MontFerret/ferret/pkg/stdlib/io/fs"
+
+	. "github.com/smartystreets/goconvey/convey"
+)
+
+func TestRead(t *testing.T) {
+
+	Convey("Arguments passed", t, func() {
+
+		Convey("No arguments passed", func() {
+			out, err := fs.Read(context.Background())
+
+			So(out, ShouldEqual, values.None)
+			So(err, ShouldBeError)
+		})
+
+		Convey("Passed not a string", func() {
+			args := []core.Value{values.NewInt(0)}
+			out, err := fs.Read(context.Background(), args...)
+
+			So(out, ShouldEqual, values.None)
+			So(err, ShouldBeError)
+		})
+
+		Convey("Passed more that one argument", func() {
+			args := []core.Value{
+				values.NewString("filepath"),
+				values.NewInt(0),
+			}
+			out, err := fs.Read(context.Background(), args...)
+
+			So(out, ShouldEqual, values.None)
+			So(err, ShouldBeError)
+		})
+	})
+
+	Convey("Read from file", t, func() {
+
+		Convey("File exists", func() {
+			file, err := ioutil.TempFile("", "readtest")
+			So(err, ShouldBeNil)
+
+			defer func() {
+				file.Close()
+				os.Remove(file.Name())
+			}()
+
+			text := "s string"
+			file.WriteString(text)
+
+			fname := values.NewString(file.Name())
+
+			out, err := fs.Read(context.Background(), fname)
+			So(err, ShouldBeNil)
+
+			So(out.Type().ID(), ShouldEqual, types.Binary.ID())
+			So(out.String(), ShouldEqual, text)
+		})
+
+		Convey("File does not exist", func() {
+			fname := values.NewString("not_exist.file")
+
+			out, err := fs.Read(context.Background(), fname)
+			So(out, ShouldEqual, values.None)
+			So(err, ShouldBeError)
+		})
+	})
+}

pkg/stdlib/io/lib.go

@@ -0,0 +1,18 @@
+package io
+
+import (
+	"github.com/MontFerret/ferret/pkg/runtime/core"
+	"github.com/MontFerret/ferret/pkg/stdlib/io/fs"
+)
+
+// RegisterLib register `IO` namespace functions.
+func RegisterLib(ns core.Namespace) error {
+	io := ns.Namespace("IO")
+
+	err := fs.RegisterLib(io)
+	if err != nil {
+		return core.Error(err, "register `FS`")
+	}
+
+	return nil
+}

pkg/stdlib/lib.go

@@ -5,6 +5,7 @@ import (
 	"github.com/MontFerret/ferret/pkg/stdlib/arrays"
 	"github.com/MontFerret/ferret/pkg/stdlib/collections"
 	"github.com/MontFerret/ferret/pkg/stdlib/html"
+	"github.com/MontFerret/ferret/pkg/stdlib/io"
 	"github.com/MontFerret/ferret/pkg/stdlib/math"
 	"github.com/MontFerret/ferret/pkg/stdlib/objects"
 	"github.com/MontFerret/ferret/pkg/stdlib/strings"
@@ -41,5 +42,9 @@ func RegisterLib(ns core.Namespace) error {
 		return err
 	}
 
+	if err := io.RegisterLib(ns); err != nil {
+		return err
+	}
+
 	return utils.RegisterLib(ns)
 }