Adding upstream version 1.34.4.

Signed-off-by: Daniel Baumann <daniel@debian.org>

internal/templating/engine.go

@@ -0,0 +1,88 @@
+package templating
+
+import (
+	"sort"
+	"strings"
+)
+
+const (
+	// DefaultSeparator is the default separation character to use when separating template parts.
+	DefaultSeparator = "."
+)
+
+// Engine uses a Matcher to retrieve the appropriate template and applies the template
+// to the input string
+type Engine struct {
+	joiner  string
+	matcher *matcher
+}
+
+// Apply extracts the template fields from the given line and returns the measurement
+// name, tags and field name
+//
+//nolint:revive //function-result-limit conditionally 4 return results allowed
+func (e *Engine) Apply(line string) (measurementName string, tags map[string]string, field string, err error) {
+	return e.matcher.match(line).Apply(line, e.joiner)
+}
+
+// NewEngine creates a new templating engine
+func NewEngine(joiner string, defaultTemplate *Template, templates []string) (*Engine, error) {
+	engine := Engine{
+		joiner:  joiner,
+		matcher: newMatcher(defaultTemplate),
+	}
+	templateSpecs := parseTemplateSpecs(templates)
+
+	for _, templateSpec := range templateSpecs {
+		if err := engine.matcher.addSpec(templateSpec); err != nil {
+			return nil, err
+		}
+	}
+
+	return &engine, nil
+}
+
+func parseTemplateSpecs(templates []string) templateSpecs {
+	tmplts := templateSpecs{}
+	for _, pattern := range templates {
+		tmplt := templateSpec{
+			separator: DefaultSeparator,
+		}
+
+		// Format is [separator] [filter] <template> [tag1=value1,tag2=value2]
+		parts := strings.Fields(pattern)
+		partsLength := len(parts)
+		if partsLength < 1 {
+			// ignore
+			continue
+		}
+		if partsLength == 1 {
+			tmplt.template = pattern
+		} else if partsLength == 4 {
+			tmplt.separator = parts[0]
+			tmplt.filter = parts[1]
+			tmplt.template = parts[2]
+			tmplt.tagstring = parts[3]
+		} else {
+			hasTagstring := strings.Contains(parts[partsLength-1], "=")
+			if hasTagstring {
+				tmplt.tagstring = parts[partsLength-1]
+				tmplt.template = parts[partsLength-2]
+				if partsLength == 3 {
+					tmplt.filter = parts[0]
+				}
+			} else {
+				tmplt.template = parts[partsLength-1]
+				if partsLength == 2 {
+					tmplt.filter = parts[0]
+				} else { // length == 3
+					tmplt.separator = parts[0]
+					tmplt.filter = parts[1]
+				}
+			}
+		}
+		tmplts = append(tmplts, tmplt)
+	}
+	sort.Sort(tmplts)
+	return tmplts
+}