Added command history (#45)

* Added command line history to the command, query and filter prompts.
* Added query planning debugging to the log.
* Fixed bug in query expression which was not treating true and false as boolean literals.
* Fixed a bug in the query planning logic which was incorrectly determine that an expression of the form sort_key ^= "string", with no partition key, could be executed as a query instead of a scan.

internal/dynamo-browse/services/historyprovider.go

@@ -0,0 +1,13 @@
+package services
+
+type HistoryProvider interface {
+	// Len returns the number of historical items
+	Len() int
+
+	// Item returns the historical item at index 'idx', where items are chronologically ordered such that the
+	// item at 0 is the oldest item.
+	Item(idx int) string
+
+	// PutItem adds an item to the history
+	PutItem(item string)
+}

internal/dynamo-browse/services/inputhistory/iface.go

@@ -0,0 +1,8 @@
+package inputhistory
+
+import "context"
+
+type HistoryItemStore interface {
+	Items(ctx context.Context, category string) ([]string, error)
+	PutItem(ctx context.Context, category string, item string) error
+}

internal/dynamo-browse/services/inputhistory/iter.go

@@ -0,0 +1,49 @@
+package inputhistory
+
+import (
+	"context"
+	"github.com/lmika/audax/internal/dynamo-browse/services"
+	"log"
+	"strings"
+)
+
+func (svc *Service) Iter(ctx context.Context, category string) services.HistoryProvider {
+	items, err := svc.store.Items(ctx, category)
+	if err != nil {
+		log.Printf("warn: cannot get iter for '%v': %v", category, err)
+		return nil
+	}
+	return &Iter{svc, items, category}
+}
+
+func (svc *Service) PutItem(ctx context.Context, category string, value string) error {
+	return svc.store.PutItem(ctx, category, value)
+}
+
+type Iter struct {
+	svc      *Service
+	items    []string
+	category string
+}
+
+func (i *Iter) Len() int {
+	return len(i.items)
+}
+
+func (i *Iter) Item(idx int) string {
+	return i.items[idx]
+}
+
+func (i *Iter) PutItem(item string) {
+	if strings.TrimSpace(item) == "" {
+		return
+	}
+
+	if len(i.items) > 0 && i.items[len(i.items)-1] == item {
+		return
+	}
+
+	if err := i.svc.PutItem(context.Background(), i.category, item); err != nil {
+		log.Printf("warn: cannot put input history: category = %v, value = %v, err = %v", i.category, item, err)
+	}
+}

internal/dynamo-browse/services/inputhistory/service.go

@@ -0,0 +1,9 @@
+package inputhistory
+
+type Service struct {
+	store HistoryItemStore
+}
+
+func New(store HistoryItemStore) *Service {
+	return &Service{store: store}
+}

internal/dynamo-browse/services/tables/service.go

@@ -59,15 +59,18 @@ func (s *Service) doScan(
 
 		runAsQuery = plan.CanQuery
 		filterExpr = &plan.Expression
+
+		log.Printf("Running query over '%v'", tableInfo.Name)
+		plan.Describe(log.Default())
+	} else {
+		log.Printf("Performing scan over '%v'", tableInfo.Name)
 	}
 
 	var results []models.Item
 	var lastEvalKey map[string]types.AttributeValue
 	if runAsQuery {
-		log.Printf("executing query")
 		results, lastEvalKey, err = s.provider.QueryItems(ctx, tableInfo.Name, filterExpr, exclusiveStartKey, limit)
 	} else {
-		log.Printf("executing scan")
 		results, lastEvalKey, err = s.provider.ScanItems(ctx, tableInfo.Name, filterExpr, exclusiveStartKey, limit)
 	}