Search API (#350)

search/handler/parser.go

@@ -0,0 +1,101 @@
+package handler
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/bitly/go-simplejson"
+)
+
+func parseQueryString(query string) (*simplejson.Json, error) {
+	_, items := lex("foo", query)
+	res, err := parseQueryStringRec(items)
+	if err != nil {
+		return nil, err
+	}
+	js := simplejson.New()
+	js.Set("query", res)
+	return js, nil
+}
+
+const (
+	matchTypeRange    = "range"
+	matchTypeMatch    = "match"
+	matchTypeWildcard = "wildcard"
+)
+
+func parseQueryStringRec(items chan item) (*simplejson.Json, error) {
+	retTerm := simplejson.New()
+	currFieldName := ""
+	currBool := ""
+	currMatchType := matchTypeMatch
+	currPathAddition := ""
+	terms := []*simplejson.Json{}
+itemLoop:
+	for it := range items {
+		if it.typ == itemError {
+			return nil, fmt.Errorf(it.val)
+		}
+
+		switch it.typ {
+		case itemIdentifier:
+			currFieldName = it.val
+		case itemString, itemBoolean, itemNumber:
+			currTerm := simplejson.New()
+			if strings.ContainsRune(it.val, '*') {
+				currMatchType = matchTypeWildcard
+				currPathAddition = "value"
+			}
+			path := []string{currMatchType, currFieldName}
+			if len(currPathAddition) > 0 {
+				path = append(path, currPathAddition)
+			}
+			currTerm.SetPath(path, it.val)
+			terms = append(terms, currTerm)
+
+			// reset
+			currFieldName = ""
+			currMatchType = matchTypeMatch
+
+		case itemBooleanOp:
+			thisBool := "must"
+			if strings.ToLower(it.val) == "or" {
+				thisBool = "should"
+			}
+			if len(currBool) == 0 {
+				currBool = thisBool
+			} else {
+				if thisBool != currBool {
+					// undefined behaviour order of precedence needs to be explicitly defined using parentheses
+					return nil, fmt.Errorf("error parsing query. Cannot mix boolean operators without explicitly defining precedence with parentheses")
+				}
+			}
+		case itemLeftParen:
+			currTerm, err := parseQueryStringRec(items)
+			if err != nil {
+				return nil, err
+			}
+			terms = append(terms, currTerm)
+		case itemRightParen:
+			break itemLoop
+		case itemOperator:
+			switch it.val {
+			case "==":
+				currMatchType = matchTypeMatch
+				currPathAddition = ""
+			case ">=":
+				currMatchType = matchTypeRange
+				currPathAddition = "gte"
+			case "<=":
+				currMatchType = matchTypeRange
+				currPathAddition = "lte"
+			}
+
+		}
+	}
+	if len(currBool) == 0 {
+		currBool = "must"
+	}
+	retTerm.SetPath([]string{"bool", currBool}, terms)
+	return retTerm, nil
+}