github.com/gohugoio/hugo@v0.88.1/tpl/template.go (about)

     1  // Copyright 2019 The Hugo Authors. All rights reserved.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  // http://www.apache.org/licenses/LICENSE-2.0
     7  //
     8  // Unless required by applicable law or agreed to in writing, software
     9  // distributed under the License is distributed on an "AS IS" BASIS,
    10  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package tpl
    15  
    16  import (
    17  	"io"
    18  	"reflect"
    19  	"regexp"
    20  
    21  	"github.com/gohugoio/hugo/output"
    22  
    23  	texttemplate "github.com/gohugoio/hugo/tpl/internal/go_templates/texttemplate"
    24  )
    25  
    26  // TemplateManager manages the collection of templates.
    27  type TemplateManager interface {
    28  	TemplateHandler
    29  	TemplateFuncGetter
    30  	AddTemplate(name, tpl string) error
    31  	MarkReady() error
    32  }
    33  
    34  // TemplateVariants describes the possible variants of a template.
    35  // All of these may be empty.
    36  type TemplateVariants struct {
    37  	Language     string
    38  	OutputFormat output.Format
    39  }
    40  
    41  // TemplateFinder finds templates.
    42  type TemplateFinder interface {
    43  	TemplateLookup
    44  	TemplateLookupVariant
    45  }
    46  
    47  // TemplateHandler finds and executes templates.
    48  type TemplateHandler interface {
    49  	TemplateFinder
    50  	Execute(t Template, wr io.Writer, data interface{}) error
    51  	LookupLayout(d output.LayoutDescriptor, f output.Format) (Template, bool, error)
    52  	HasTemplate(name string) bool
    53  }
    54  
    55  type TemplateLookup interface {
    56  	Lookup(name string) (Template, bool)
    57  }
    58  
    59  type TemplateLookupVariant interface {
    60  	// TODO(bep) this currently only works for shortcodes.
    61  	// We may unify and expand this variant pattern to the
    62  	// other templates, but we need this now for the shortcodes to
    63  	// quickly determine if a shortcode has a template for a given
    64  	// output format.
    65  	// It returns the template, if it was found or not and if there are
    66  	// alternative representations (output format, language).
    67  	// We are currently only interested in output formats, so we should improve
    68  	// this for speed.
    69  	LookupVariant(name string, variants TemplateVariants) (Template, bool, bool)
    70  	LookupVariants(name string) []Template
    71  }
    72  
    73  // Template is the common interface between text/template and html/template.
    74  type Template interface {
    75  	Name() string
    76  	Prepare() (*texttemplate.Template, error)
    77  }
    78  
    79  // TemplateParser is used to parse ad-hoc templates, e.g. in the Resource chain.
    80  type TemplateParser interface {
    81  	Parse(name, tpl string) (Template, error)
    82  }
    83  
    84  // TemplateParseFinder provides both parsing and finding.
    85  type TemplateParseFinder interface {
    86  	TemplateParser
    87  	TemplateFinder
    88  }
    89  
    90  // TemplateDebugger prints some debug info to stdout.
    91  type TemplateDebugger interface {
    92  	Debug()
    93  }
    94  
    95  // templateInfo wraps a Template with some additional information.
    96  type templateInfo struct {
    97  	Template
    98  	Info
    99  }
   100  
   101  // templateInfo wraps a Template with some additional information.
   102  type templateInfoManager struct {
   103  	Template
   104  	InfoManager
   105  }
   106  
   107  // TemplatesProvider as implemented by deps.Deps.
   108  type TemplatesProvider interface {
   109  	Tmpl() TemplateHandler
   110  	TextTmpl() TemplateParseFinder
   111  }
   112  
   113  // WithInfo wraps the info in a template.
   114  func WithInfo(templ Template, info Info) Template {
   115  	if manager, ok := info.(InfoManager); ok {
   116  		return &templateInfoManager{
   117  			Template:    templ,
   118  			InfoManager: manager,
   119  		}
   120  	}
   121  
   122  	return &templateInfo{
   123  		Template: templ,
   124  		Info:     info,
   125  	}
   126  }
   127  
   128  var baseOfRe = regexp.MustCompile("template: (.*?):")
   129  
   130  func extractBaseOf(err string) string {
   131  	m := baseOfRe.FindStringSubmatch(err)
   132  	if len(m) == 2 {
   133  		return m[1]
   134  	}
   135  	return ""
   136  }
   137  
   138  // TemplateFuncGetter allows to find a template func by name.
   139  type TemplateFuncGetter interface {
   140  	GetFunc(name string) (reflect.Value, bool)
   141  }