chore: add miniparse pkg for future .mini config files (#49)

* chore: add miniparse pkg for future .mini config files

* chore: refactor to func state machine

* chore: support reflection for one struct

* test: add parse errors test

* test: more corner cases; fix: panic without root section

* chore: minor reflect patch

* test: add reflection tests

* feat: support section arrays; test: more reflection

* feat: add mini-required tag

* feat: add duration reflect type

* feat: add mini-default tag

* docs: add docs to Decode func

.golangci.yml

@@ -11,6 +11,7 @@ linters:
     - varnamelen
     - godox
     - exportloopref
+    - tagalign # alignment looks awful
 
 linters-settings:
   cyclop:

pkg/miniparse/miniparse.go

@@ -0,0 +1,72 @@
+package miniparse
+
+import (
+	"bufio"
+	"errors"
+	"io"
+	"reflect"
+)
+
+var (
+	ErrLeadingSpace    = errors.New("leading spaces are not allowed")
+	ErrInvalidChar     = errors.New("invalid leading char")
+	ErrExpectedNewLine = errors.New("expected new line")
+	ErrInvalidSection  = errors.New("invalid section name")
+	ErrRootSection     = errors.New("expected root section")
+	ErrInvalidKey      = errors.New("invalid key name")
+	ErrExpectedEqual   = errors.New("expected equal sign")
+	ErrExpectedSpace   = errors.New("expected space")
+	ErrUnexpectedEOF   = errors.New("unexpected end of file")
+
+	ErrExpectedPointer = errors.New("expected not nil pointer")
+	ErrExpectedStruct  = errors.New("expected struct")
+	ErrBadSectionType  = errors.New("bad section type")
+	ErrBadRecordType   = errors.New("bad record type")
+	ErrExpectedArray   = errors.New("expected array")
+	ErrRequiredField   = errors.New("field marked required")
+)
+
+// Decode .mini config file into value using reflect.
+// The mini format is similar to ini, but very strict.
+//
+// Each line of the config must be one of the following: blank, comment, record title, record field.
+// Leading spaces are not allowed. End-of-line spaces are only allowed in record field lines.
+// A non-empty .mini config file must end with a blank string.
+// A comment must begin with a '#' character. All comments will be ignored by the parser.
+// The record title must be "[title]", where title is the non-empty name of the varname.
+// Varnames contain only lowercase ascii letters, digits and the '_' character.
+// The first letter of the varname must not be a digit.
+// The record field must have the form “key = value”, where key is a non-empty varname.
+// The value contains any valid utf-8 sequence.
+// Record names and keys can be non-unique. Then they will be interpreted as arrays.
+//
+// The mini format does not specify data types of values.
+// But this decoder works only with string, int, bool and time.Duration.
+// You should use `mini:"name"` tag to designate a structure field.
+// You can use the `mini-required:"true"` tag for mandatory fields.
+// You can use the `mini-default:"value"` tag for default values.
+func Decode(r io.Reader, v any) error {
+	rb := bufio.NewReader(r)
+	m := newMachine()
+	nxt := m.stateInit
+
+	for {
+		c, _, err := rb.ReadRune()
+		if errors.Is(err, io.EOF) {
+			break
+		}
+		if err != nil {
+			return err
+		}
+		nxt, err = nxt(c)
+		if err != nil {
+			return err
+		}
+	}
+	// TODO: find more Go-like solution
+	if reflect.ValueOf(nxt).Pointer() != reflect.ValueOf(m.stateInit).Pointer() {
+		return ErrUnexpectedEOF
+	}
+
+	return m.feed(v)
+}

pkg/miniparse/miniparse_test.go

@@ -0,0 +1,246 @@
+package miniparse_test
+
+import (
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/Gornak40/algolymp/pkg/miniparse"
+	"github.com/stretchr/testify/require"
+)
+
+const coreMini = `[core]
+# year is just for fun
+id = avx2024
+name = AVX инструкции с нуля 🦍
+
+number_id = 2812
+number_id = 1233
+public = 1
+contest_id = 33
+magic = -1
+
+flags = false
+flags = true
+flags = T
+
+contest_id = 12312
+contest_id = 9012
+
+[standings]
+id = avx2024_fall
+type = acm
+# visible names
+public = true
+
+[standings]
+id = avx2024_aesc
+type = acm
+refresh_delay = 60s
+
+[penalty]
+id = avx2024_pen
+ban = 1440m
+ban = 72h
+
+[penalty]
+id = avx2024_aesc_pen
+value = 100
+`
+
+type core struct {
+	ID        string `mini:"id" mini-required:"true"`
+	Name      string `mini:"name"`
+	NumberID  []int  `mini:"number_id"`
+	Public    bool   `mini:"public"`
+	Empty     string
+	Flags     []bool   `mini:"flags"`
+	ContestID []string `mini:"contest_id"`
+	Magic     int      `mini:"magic"`
+}
+
+type standings struct {
+	ID           string        `mini:"id" mini-required:"true"`
+	Type         string        `mini:"type"`
+	Public       bool          `mini:"public"`
+	RefreshDelay time.Duration `mini:"refresh_delay"`
+}
+
+type penalty struct {
+	ID    string          `mini:"id" mini-required:"true"`
+	Ban   []time.Duration `mini:"ban" mini-default:"3h30m"`
+	Value int             `mini:"value" mini-default:"50"`
+}
+
+type config struct {
+	Core      core        `mini:"core"`
+	Standings []standings `mini:"standings"`
+	Penalty   []penalty   `mini:"penalty"`
+}
+
+func TestReflect(t *testing.T) {
+	t.Parallel()
+	var ss config
+
+	r := strings.NewReader(coreMini)
+	require.NoError(t, miniparse.Decode(r, &ss))
+	require.Equal(t, config{
+		Core: core{
+			ID:        "avx2024",
+			Name:      "AVX инструкции с нуля 🦍",
+			NumberID:  []int{2812, 1233},
+			Public:    true,
+			Flags:     []bool{false, true, true},
+			ContestID: []string{"33", "12312", "9012"},
+			Magic:     -1,
+		},
+		Standings: []standings{
+			{
+				ID:     "avx2024_fall",
+				Type:   "acm",
+				Public: true,
+			},
+			{
+				ID:           "avx2024_aesc",
+				Type:         "acm",
+				RefreshDelay: time.Minute,
+			},
+		},
+		Penalty: []penalty{
+			{
+				ID:    "avx2024_pen",
+				Ban:   []time.Duration{24 * time.Hour, 72 * time.Hour},
+				Value: 50,
+			},
+			{
+				ID:    "avx2024_aesc_pen",
+				Ban:   []time.Duration{210 * time.Minute},
+				Value: 100,
+			},
+		},
+	}, ss)
+}
+
+func TestCorner(t *testing.T) {
+	t.Parallel()
+	var ss struct{}
+	tt := []string{
+		"",
+		"[alone]\n",
+		"\n",
+		"[empty]\n[empty]\n[again]\n",
+		"[rune]\nkey = [section]\n[section]\nkey2 = 0\n",
+	}
+
+	for _, s := range tt {
+		r := strings.NewReader(s)
+		require.NoError(t, miniparse.Decode(r, &ss))
+	}
+}
+
+func TestParseError(t *testing.T) {
+	t.Parallel()
+	var ss struct{}
+	tt := map[string]error{
+		"[html page]\n":                            miniparse.ErrInvalidSection,
+		"[htmlPage]\n":                             miniparse.ErrInvalidSection,
+		"[1html]\n":                                miniparse.ErrInvalidSection,
+		"[html]":                                   miniparse.ErrUnexpectedEOF,
+		"[html":                                    miniparse.ErrUnexpectedEOF,
+		"[html]\n]":                                miniparse.ErrInvalidChar,
+		"[html]\nkey\n":                            miniparse.ErrInvalidKey,
+		"[html]\nkey=value\n":                      miniparse.ErrInvalidKey,
+		"[html]\nKEY = value\n":                    miniparse.ErrInvalidChar,
+		"[html]\n1key = value\n":                   miniparse.ErrInvalidChar,
+		"[html]\nkey= value\n":                     miniparse.ErrInvalidKey,
+		"[html]\nkey =value\n":                     miniparse.ErrExpectedSpace,
+		"[html]\nkey = value":                      miniparse.ErrUnexpectedEOF,
+		"[html]\nkey  = value\n":                   miniparse.ErrExpectedEqual,
+		"[html]\nkey = value[html]\n[html]":        miniparse.ErrUnexpectedEOF,
+		"[html] # section\n":                       miniparse.ErrExpectedNewLine,
+		"# section\n[html]\nkey = 1\nkey2\n":       miniparse.ErrInvalidKey,
+		"[html]\nkey = \"bababababayka\nbrrry\"\n": miniparse.ErrInvalidKey,
+		" [html]\n":                                miniparse.ErrLeadingSpace,
+		"[html]\n key = value\n":                   miniparse.ErrLeadingSpace,
+		"[html]\n = value\n":                       miniparse.ErrLeadingSpace,
+		"key = value\n":                            miniparse.ErrRootSection,
+	}
+
+	for s, terr := range tt {
+		r := strings.NewReader(s)
+		require.ErrorIs(t, miniparse.Decode(r, &ss), terr)
+	}
+}
+
+func TestReflectArgError(t *testing.T) {
+	t.Parallel()
+
+	m := make(map[string]any)
+	require.ErrorIs(t, miniparse.Decode(strings.NewReader(""), m), miniparse.ErrExpectedPointer)
+	require.ErrorIs(t, miniparse.Decode(strings.NewReader(""), &m), miniparse.ErrExpectedStruct)
+	require.ErrorIs(t, miniparse.Decode(strings.NewReader(""), nil), miniparse.ErrExpectedPointer)
+
+	x := 4
+	require.ErrorIs(t, miniparse.Decode(strings.NewReader(""), &x), miniparse.ErrExpectedStruct)
+	require.ErrorIs(t, miniparse.Decode(strings.NewReader(""), "gorill"), miniparse.ErrExpectedPointer)
+
+	var ss struct{}
+	require.ErrorIs(t, miniparse.Decode(strings.NewReader(""), ss), miniparse.ErrExpectedPointer)
+}
+
+const htmlMini = `[html]
+page_id = 14141
+preload = true
+# wow! a comment
+page_id = 99119
+name = Bob
+`
+
+func TestReflectError(t *testing.T) {
+	t.Parallel()
+	r := strings.NewReader(htmlMini)
+	var ss2 struct {
+		HTML struct {
+			PageID []struct {
+				Key   string `mini:"key"`
+				Value string `mini:"value"`
+			} `mini:"page_id"`
+		} `mini:"html"`
+	}
+	require.ErrorIs(t, miniparse.Decode(r, &ss2), miniparse.ErrBadRecordType)
+
+	r.Reset(htmlMini)
+	var ss3 struct {
+		HTML struct {
+			Name   string `mini:"name"`
+			PageID int    `mini:"page_id"`
+		} `mini:"html"`
+	}
+	require.ErrorIs(t, miniparse.Decode(r, &ss3), miniparse.ErrExpectedArray)
+
+	r.Reset(htmlMini)
+	var ss4 struct {
+		HTML []map[string]any `mini:"html"`
+	}
+	require.ErrorIs(t, miniparse.Decode(r, &ss4), miniparse.ErrExpectedStruct)
+
+	r.Reset(htmlMini)
+	var ss5 struct {
+		HTML struct {
+		} `mini:"html"`
+		CSS []struct {
+		} `mini:"css" mini-required:"true"`
+	}
+	require.ErrorIs(t, miniparse.Decode(r, &ss5), miniparse.ErrRequiredField)
+
+	r.Reset(htmlMini)
+	var ss6 struct {
+		HTML struct {
+			Name string `mini:"name" mini-required:"true"`
+			ID   int    `mini:"id" mini-required:"true"`
+		} `mini:"html"`
+		CSS []struct {
+		} `mini:"css"`
+	}
+	require.ErrorIs(t, miniparse.Decode(r, &ss6), miniparse.ErrRequiredField)
+}