deploytool: Add README.md, migrate docs to it.

deploytool/cmd/param.go

Index: deploytool/cmd/param.go
diff --git a/deploytool/cmd/param.go b/deploytool/cmd/param.go
deleted file mode 100644
index 42161228a786f4cfc313717f854f84de84e56931..0000000000000000000000000000000000000000
--- a/deploytool/cmd/param.go
+++ /dev/null
@@ -1,51 +0,0 @@
-// Copyright 2016 The LUCI Authors. All rights reserved.
-// Use of this source code is governed under the Apache License, Version 2.0
-// that can be found in the LICENSE file.
-
-package main
-
-import (
-	"regexp"
-	"strings"
-
-	"github.com/luci/luci-go/common/errors"
-)
-
-// paramRE is the regular expression for deployment parameter substitution.
-//
-// Keys can contain alphanumeric letters plus underscores and periods.
-// Substitution is represented as ${KEY}.
-var paramRE = regexp.MustCompile(`\${([a-zA-Z0-9_.]+)}`)
-
-// substitute substitutes any parameter expressions with a value from the
-// supplied substitution map. If a parameter is referenced but not defined,
-// an error will be returned.
-func substitute(vp *string, subs map[string]string) error {
-	var (
-		v       = *vp
-		matches = paramRE.FindAllStringSubmatchIndex(v, -1)
-		parts   = make([]string, 0, (len(matches)*2)+1)
-		sidx    = 0
-	)
-	for _, m := range matches {
-		// m will have 4 entries:
-		// v[m[0]:m[1]] is the variable expression that was matched.
-		// v[m[2]:m[3]] is the paramter key (first capture group)
-		parts = append(parts, v[sidx:m[0]])
-		sidx = m[1]
-
-		key := v[m[2]:m[3]]
-		if val, ok := subs[key]; ok {
-			parts = append(parts, val)
-		} else {
-			// panic to immediately stop matching. This will be caught at the top of
-			// this function.
-			return errors.Reason("undefined parameter %(key)q").D("key", key).Err()
-		}
-	}
-
-	// Finish the string and return.
-	parts = append(parts, v[sidx:])
-	*vp = strings.Join(parts, "")
-	return nil
-}