Conversion rules are not cooperating. (75ef492a) · Commits · Kevin Lyda / units

rules/rules.go

+63 −26

Original line number	Diff line number	Diff line
		@@ -20,10 +20,12 @@ var (
		unit_kind(c, temperature).
		unit_kind(m2, area).
		unit_kind(cm2, area).
		unit_kind(mm, distance).
		unit_kind(cm, distance).
		unit_kind(m, distance).
		unit_kind(km, distance).
		unit_kind(feet, distance).
		unit_kind(mg, mass).
		unit_kind(g, mass).
		unit_kind(kg, mass).
		unit_kind(lb, mass).
		@@ -41,13 +43,36 @@ rule(GivenQuant, c, TargetQuant, k) :-
		TargetQuant is GivenQuant + 273.15.
		rule(GivenQuant, k, TargetQuant, c) :-
		TargetQuant is GivenQuant - 273.15.

		rule(GivenQuant, GivenUnit, TargetQuant, TargetUnit) :-
		rule(GivenQuant, GivenUnit, X, Y),
		rule(X, Y, TargetQuant, TargetUnit).

		ratio(m, km, 0.001).
		ratio(m, cm, 100).
		ratio(m, mm, 1000).
		ratio(feet, m, 0.3048).
		ratio(feet, inches, 12).

		ratio(g, mg, 1000).
		ratio(g, kg, 0.001).

		ratio(X, Y, Ratio) :- ratio(Y, X, Z), Ratio is 1/Z, !.
		ratio(X, Y, Ratio) :-
		ratio(Y, Step, R1),
		ratio(Step, Z, R2),
		Step =\= Y,
		Step =\= Z,
		Ratio is R1 * R2, !.

		convert(GivenQuant, GivenUnit, TargetQuant, TargetUnit) :-
		unit_kind(GivenUnit, temperature),
		unit_kind(TargetUnit, temperature),
		rule(GivenQuant, GivenUnit, TargetQuant, TargetUnit).
		convert(GivenQuant, GivenUnit, TargetQuant, TargetUnit) :-
		write("foo"), nl,
		ratio(GivenUnit, TargetUnit, Ratio),
		TargetQuant is GivenQuant * Ratio, !.
		`
		)

		@@ -60,6 +85,9 @@ func New() (*Engine, error) {
		if err := ngn.p.Exec(`:- set_prolog_flag(double_quotes, atom).`); err != nil {
		return nil, err
		}
		if err := ngn.p.Exec(`:- set_prolog_flag(debug, on).`); err != nil {
		return nil, err
		}

		if err := ngn.p.Exec(prologKinds); err != nil {
		return nil, err
		@@ -98,22 +126,31 @@ func (ngn *Engine) Kind(unit string) (string, error) {

		// Convert converts units.
		func (ngn *Engine) Convert(qty float64, givenUnit, targetUnit string) (float64, error) {
		sols, err := ngn.p.Query("convert(?, ?, Qty, ?).", qty, givenUnit, targetUnit)
		sol := ngn.p.QuerySolution("convert(?, ?, Qty, ?).", qty, givenUnit, targetUnit)
		if sol == nil {
		fmt.Println("sol == nil")
		return 0, errors.New("Query failed")
		}
		err := sol.Err()
		if err != nil {
		fmt.Println("Huh?")
		fmt.Println("sol.Err()")
		return 0, err
		}
		defer sols.Close()

		for sols.Next() {
		var quantity struct {
		Qty float64
		}
		if err := sols.Scan(&quantity); err != nil {
		fmt.Println("Scan?")
		return 0, err
		}
		err = sol.Scan(&quantity)
		if err == nil {
		fmt.Println("got qty")
		return quantity.Qty, err
		}
		fmt.Println("qty scan failed")
		var dbg []byte
		if err := sol.Scan(&dbg); err != nil {
		fmt.Println("on dbg scan")
		return 0, err
		}
		fmt.Printf("dbg: '%s'\n", dbg)
		return 0, err
		}

rules/rules_test.go

+15 −13

Original line number	Diff line number	Diff line
		@@ -4,6 +4,7 @@ import (
		"testing"

		"github.com/stretchr/testify/assert"
		"github.com/stretchr/testify/require"
		)

		func TestKinds(t *testing.T) {
		@@ -20,11 +21,11 @@ func TestKinds(t *testing.T) {
		}

		ngn, err := New()
		assert.NoError(t, err)
		require.NoError(t, err)
		for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
		result, err := ngn.Kind(tc.query)
		assert.NoError(t, err)
		require.NoError(t, err)

		assert.Equal(t, tc.result, result)
		})
		@@ -36,31 +37,32 @@ func TestConverts(t *testing.T) {
		name string
		qty float64
		given string
		target string
		result float64
		target string
		}{
		{
		"c to f",
		22.0,
		"c",
		"f",
		71.6,
		22.0, "c",
		71.6, "f",
		},
		{
		"k to f",
		22.0,
		"k",
		"f",
		-420.07,
		22.0, "k",
		-420.07, "f",
		},
		{
		"inches to cm",
		2.0, "inches",
		5.08, "cm",
		},
		}

		ngn, err := New()
		assert.NoError(t, err)
		require.NoError(t, err)
		for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
		result, err := ngn.Convert(tc.qty, tc.given, tc.target)
		assert.NoError(t, err)
		require.NoError(t, err)

		assert.InDelta(t, tc.result, result, 0.1)
		})