diff options
Diffstat (limited to 'tpl/internal/go_templates/texttemplate/template.go')
-rw-r--r-- | tpl/internal/go_templates/texttemplate/template.go | 228 |
1 files changed, 228 insertions, 0 deletions
diff --git a/tpl/internal/go_templates/texttemplate/template.go b/tpl/internal/go_templates/texttemplate/template.go new file mode 100644 index 000000000..4df8a9ed0 --- /dev/null +++ b/tpl/internal/go_templates/texttemplate/template.go @@ -0,0 +1,228 @@ +// Copyright 2011 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package template + +import ( + "github.com/gohugoio/hugo/tpl/internal/go_templates/texttemplate/parse" + "reflect" + "sync" +) + +// common holds the information shared by related templates. +type common struct { + tmpl map[string]*Template // Map from name to defined templates. + option option + // We use two maps, one for parsing and one for execution. + // This separation makes the API cleaner since it doesn't + // expose reflection to the client. + muFuncs sync.RWMutex // protects parseFuncs and execFuncs + parseFuncs FuncMap + execFuncs map[string]reflect.Value +} + +// Template is the representation of a parsed template. The *parse.Tree +// field is exported only for use by html/template and should be treated +// as unexported by all other clients. +type Template struct { + name string + *parse.Tree + *common + leftDelim string + rightDelim string +} + +// New allocates a new, undefined template with the given name. +func New(name string) *Template { + t := &Template{ + name: name, + } + t.init() + return t +} + +// Name returns the name of the template. +func (t *Template) Name() string { + return t.name +} + +// New allocates a new, undefined template associated with the given one and with the same +// delimiters. The association, which is transitive, allows one template to +// invoke another with a {{template}} action. +// +// Because associated templates share underlying data, template construction +// cannot be done safely in parallel. Once the templates are constructed, they +// can be executed in parallel. +func (t *Template) New(name string) *Template { + t.init() + nt := &Template{ + name: name, + common: t.common, + leftDelim: t.leftDelim, + rightDelim: t.rightDelim, + } + return nt +} + +// init guarantees that t has a valid common structure. +func (t *Template) init() { + if t.common == nil { + c := new(common) + c.tmpl = make(map[string]*Template) + c.parseFuncs = make(FuncMap) + c.execFuncs = make(map[string]reflect.Value) + t.common = c + } +} + +// Clone returns a duplicate of the template, including all associated +// templates. The actual representation is not copied, but the name space of +// associated templates is, so further calls to Parse in the copy will add +// templates to the copy but not to the original. Clone can be used to prepare +// common templates and use them with variant definitions for other templates +// by adding the variants after the clone is made. +func (t *Template) Clone() (*Template, error) { + nt := t.copy(nil) + nt.init() + if t.common == nil { + return nt, nil + } + for k, v := range t.tmpl { + if k == t.name { + nt.tmpl[t.name] = nt + continue + } + // The associated templates share nt's common structure. + tmpl := v.copy(nt.common) + nt.tmpl[k] = tmpl + } + t.muFuncs.RLock() + defer t.muFuncs.RUnlock() + for k, v := range t.parseFuncs { + nt.parseFuncs[k] = v + } + for k, v := range t.execFuncs { + nt.execFuncs[k] = v + } + return nt, nil +} + +// copy returns a shallow copy of t, with common set to the argument. +func (t *Template) copy(c *common) *Template { + nt := New(t.name) + nt.Tree = t.Tree + nt.common = c + nt.leftDelim = t.leftDelim + nt.rightDelim = t.rightDelim + return nt +} + +// AddParseTree adds parse tree for template with given name and associates it with t. +// If the template does not already exist, it will create a new one. +// If the template does exist, it will be replaced. +func (t *Template) AddParseTree(name string, tree *parse.Tree) (*Template, error) { + t.init() + // If the name is the name of this template, overwrite this template. + nt := t + if name != t.name { + nt = t.New(name) + } + // Even if nt == t, we need to install it in the common.tmpl map. + if t.associate(nt, tree) || nt.Tree == nil { + nt.Tree = tree + } + return nt, nil +} + +// Templates returns a slice of defined templates associated with t. +func (t *Template) Templates() []*Template { + if t.common == nil { + return nil + } + // Return a slice so we don't expose the map. + m := make([]*Template, 0, len(t.tmpl)) + for _, v := range t.tmpl { + m = append(m, v) + } + return m +} + +// Delims sets the action delimiters to the specified strings, to be used in +// subsequent calls to Parse, ParseFiles, or ParseGlob. Nested template +// definitions will inherit the settings. An empty delimiter stands for the +// corresponding default: {{ or }}. +// The return value is the template, so calls can be chained. +func (t *Template) Delims(left, right string) *Template { + t.init() + t.leftDelim = left + t.rightDelim = right + return t +} + +// Funcs adds the elements of the argument map to the template's function map. +// It must be called before the template is parsed. +// It panics if a value in the map is not a function with appropriate return +// type or if the name cannot be used syntactically as a function in a template. +// It is legal to overwrite elements of the map. The return value is the template, +// so calls can be chained. +func (t *Template) Funcs(funcMap FuncMap) *Template { + t.init() + t.muFuncs.Lock() + defer t.muFuncs.Unlock() + addValueFuncs(t.execFuncs, funcMap) + addFuncs(t.parseFuncs, funcMap) + return t +} + +// Lookup returns the template with the given name that is associated with t. +// It returns nil if there is no such template or the template has no definition. +func (t *Template) Lookup(name string) *Template { + if t.common == nil { + return nil + } + return t.tmpl[name] +} + +// Parse parses text as a template body for t. +// Named template definitions ({{define ...}} or {{block ...}} statements) in text +// define additional templates associated with t and are removed from the +// definition of t itself. +// +// Templates can be redefined in successive calls to Parse. +// A template definition with a body containing only white space and comments +// is considered empty and will not replace an existing template's body. +// This allows using Parse to add new named template definitions without +// overwriting the main template body. +func (t *Template) Parse(text string) (*Template, error) { + t.init() + t.muFuncs.RLock() + trees, err := parse.Parse(t.name, text, t.leftDelim, t.rightDelim, t.parseFuncs, builtins) + t.muFuncs.RUnlock() + if err != nil { + return nil, err + } + // Add the newly parsed trees, including the one for t, into our common structure. + for name, tree := range trees { + if _, err := t.AddParseTree(name, tree); err != nil { + return nil, err + } + } + return t, nil +} + +// associate installs the new template into the group of templates associated +// with t. The two are already known to share the common structure. +// The boolean return value reports whether to store this tree as t.Tree. +func (t *Template) associate(new *Template, tree *parse.Tree) bool { + if new.common != t.common { + panic("internal error: associate not common") + } + if old := t.tmpl[new.name]; old != nil && parse.IsEmptyTree(tree.Root) && old.Tree != nil { + // If a template by that name exists, + // don't replace it with an empty template. + return false + } + t.tmpl[new.name] = new + return true +} |