reorganize: starting with funcs

28-methods/xxx-log-parser-methods/parser.go

@@ -0,0 +1,40 @@
+package main
+
+import (
+	"fmt"
+)
+
+// parser keep tracks of the parsing
+type parser struct {
+	lines int   // number of parsed lines (for the error messages)
+	lerr  error // the last error occurred
+}
+
+// parsed wraps a result for generating parser error
+type parsed struct {
+	result       // use struct embedding
+	err    error // inject an error
+}
+
+// parse parses a log line and returns a result with an injected error
+func (p *parser) parse(line string) (pv parsed) {
+	// always set the error
+	defer func() { pv.err = p.lerr }()
+
+	// if there was an error do not continue
+	if p.lerr != nil {
+		return
+	}
+
+	// chain the parser's error to the result's
+	res, err := parseLine(line)
+	if p.lines++; err != nil {
+		p.lerr = fmt.Errorf("%s: (line #%d)", err, p.lines)
+	}
+	return parsed{result: res}
+}
+
+// err returns the last error encountered
+func (p *parser) err() error {
+	return p.lerr
+}