Use compose-spec parser

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

vendor/github.com/compose-spec/compose-go/template/template.go

@@ -0,0 +1,269 @@
+/*
+   Copyright 2020 The Compose Specification Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package template
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+var delimiter = "\\$"
+var substitution = "[_a-z][_a-z0-9]*(?::?[-?][^}]*)?"
+
+var patternString = fmt.Sprintf(
+	"%s(?i:(?P<escaped>%s)|(?P<named>%s)|{(?P<braced>%s)}|(?P<invalid>))",
+	delimiter, delimiter, substitution, substitution,
+)
+
+var defaultPattern = regexp.MustCompile(patternString)
+
+// DefaultSubstituteFuncs contains the default SubstituteFunc used by the docker cli
+var DefaultSubstituteFuncs = []SubstituteFunc{
+	softDefault,
+	hardDefault,
+	requiredNonEmpty,
+	required,
+}
+
+// InvalidTemplateError is returned when a variable template is not in a valid
+// format
+type InvalidTemplateError struct {
+	Template string
+}
+
+func (e InvalidTemplateError) Error() string {
+	return fmt.Sprintf("Invalid template: %#v", e.Template)
+}
+
+// Mapping is a user-supplied function which maps from variable names to values.
+// Returns the value as a string and a bool indicating whether
+// the value is present, to distinguish between an empty string
+// and the absence of a value.
+type Mapping func(string) (string, bool)
+
+// SubstituteFunc is a user-supplied function that apply substitution.
+// Returns the value as a string, a bool indicating if the function could apply
+// the substitution and an error.
+type SubstituteFunc func(string, Mapping) (string, bool, error)
+
+// SubstituteWith subsitute variables in the string with their values.
+// It accepts additional substitute function.
+func SubstituteWith(template string, mapping Mapping, pattern *regexp.Regexp, subsFuncs ...SubstituteFunc) (string, error) {
+	var err error
+	result := pattern.ReplaceAllStringFunc(template, func(substring string) string {
+		matches := pattern.FindStringSubmatch(substring)
+		groups := matchGroups(matches, pattern)
+		if escaped := groups["escaped"]; escaped != "" {
+			return escaped
+		}
+
+		substitution := groups["named"]
+		if substitution == "" {
+			substitution = groups["braced"]
+		}
+
+		if substitution == "" {
+			err = &InvalidTemplateError{Template: template}
+			return ""
+		}
+
+		for _, f := range subsFuncs {
+			var (
+				value   string
+				applied bool
+			)
+			value, applied, err = f(substitution, mapping)
+			if err != nil {
+				return ""
+			}
+			if !applied {
+				continue
+			}
+			return value
+		}
+
+		value, _ := mapping(substitution)
+		return value
+	})
+
+	return result, err
+}
+
+// Substitute variables in the string with their values
+func Substitute(template string, mapping Mapping) (string, error) {
+	return SubstituteWith(template, mapping, defaultPattern, DefaultSubstituteFuncs...)
+}
+
+// ExtractVariables returns a map of all the variables defined in the specified
+// composefile (dict representation) and their default value if any.
+func ExtractVariables(configDict map[string]interface{}, pattern *regexp.Regexp) map[string]Variable {
+	if pattern == nil {
+		pattern = defaultPattern
+	}
+	return recurseExtract(configDict, pattern)
+}
+
+func recurseExtract(value interface{}, pattern *regexp.Regexp) map[string]Variable {
+	m := map[string]Variable{}
+
+	switch value := value.(type) {
+	case string:
+		if values, is := extractVariable(value, pattern); is {
+			for _, v := range values {
+				m[v.Name] = v
+			}
+		}
+	case map[string]interface{}:
+		for _, elem := range value {
+			submap := recurseExtract(elem, pattern)
+			for key, value := range submap {
+				m[key] = value
+			}
+		}
+
+	case []interface{}:
+		for _, elem := range value {
+			if values, is := extractVariable(elem, pattern); is {
+				for _, v := range values {
+					m[v.Name] = v
+				}
+			}
+		}
+	}
+
+	return m
+}
+
+type Variable struct {
+	Name         string
+	DefaultValue string
+	Required     bool
+}
+
+func extractVariable(value interface{}, pattern *regexp.Regexp) ([]Variable, bool) {
+	sValue, ok := value.(string)
+	if !ok {
+		return []Variable{}, false
+	}
+	matches := pattern.FindAllStringSubmatch(sValue, -1)
+	if len(matches) == 0 {
+		return []Variable{}, false
+	}
+	values := []Variable{}
+	for _, match := range matches {
+		groups := matchGroups(match, pattern)
+		if escaped := groups["escaped"]; escaped != "" {
+			continue
+		}
+		val := groups["named"]
+		if val == "" {
+			val = groups["braced"]
+		}
+		name := val
+		var defaultValue string
+		var required bool
+		switch {
+		case strings.Contains(val, ":?"):
+			name, _ = partition(val, ":?")
+			required = true
+		case strings.Contains(val, "?"):
+			name, _ = partition(val, "?")
+			required = true
+		case strings.Contains(val, ":-"):
+			name, defaultValue = partition(val, ":-")
+		case strings.Contains(val, "-"):
+			name, defaultValue = partition(val, "-")
+		}
+		values = append(values, Variable{
+			Name:         name,
+			DefaultValue: defaultValue,
+			Required:     required,
+		})
+	}
+	return values, len(values) > 0
+}
+
+// Soft default (fall back if unset or empty)
+func softDefault(substitution string, mapping Mapping) (string, bool, error) {
+	sep := ":-"
+	if !strings.Contains(substitution, sep) {
+		return "", false, nil
+	}
+	name, defaultValue := partition(substitution, sep)
+	value, ok := mapping(name)
+	if !ok || value == "" {
+		return defaultValue, true, nil
+	}
+	return value, true, nil
+}
+
+// Hard default (fall back if-and-only-if empty)
+func hardDefault(substitution string, mapping Mapping) (string, bool, error) {
+	sep := "-"
+	if !strings.Contains(substitution, sep) {
+		return "", false, nil
+	}
+	name, defaultValue := partition(substitution, sep)
+	value, ok := mapping(name)
+	if !ok {
+		return defaultValue, true, nil
+	}
+	return value, true, nil
+}
+
+func requiredNonEmpty(substitution string, mapping Mapping) (string, bool, error) {
+	return withRequired(substitution, mapping, ":?", func(v string) bool { return v != "" })
+}
+
+func required(substitution string, mapping Mapping) (string, bool, error) {
+	return withRequired(substitution, mapping, "?", func(_ string) bool { return true })
+}
+
+func withRequired(substitution string, mapping Mapping, sep string, valid func(string) bool) (string, bool, error) {
+	if !strings.Contains(substitution, sep) {
+		return "", false, nil
+	}
+	name, errorMessage := partition(substitution, sep)
+	value, ok := mapping(name)
+	if !ok || !valid(value) {
+		return "", true, &InvalidTemplateError{
+			Template: fmt.Sprintf("required variable %s is missing a value: %s", name, errorMessage),
+		}
+	}
+	return value, true, nil
+}
+
+func matchGroups(matches []string, pattern *regexp.Regexp) map[string]string {
+	groups := make(map[string]string)
+	for i, name := range pattern.SubexpNames()[1:] {
+		groups[name] = matches[i+1]
+	}
+	return groups
+}
+
+// Split the string at the first occurrence of sep, and return the part before the separator,
+// and the part after the separator.
+//
+// If the separator is not found, return the string itself, followed by an empty string.
+func partition(s, sep string) (string, string) {
+	if strings.Contains(s, sep) {
+		parts := strings.SplitN(s, sep, 2)
+		return parts[0], parts[1]
+	}
+	return s, ""
+}