diff options
Diffstat (limited to 'src/pkg/template/execute.go')
-rw-r--r-- | src/pkg/template/execute.go | 346 |
1 files changed, 0 insertions, 346 deletions
diff --git a/src/pkg/template/execute.go b/src/pkg/template/execute.go deleted file mode 100644 index 464b620c9..000000000 --- a/src/pkg/template/execute.go +++ /dev/null @@ -1,346 +0,0 @@ -// Copyright 2009 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. - -// Code to execute a parsed template. - -package template - -import ( - "bytes" - "io" - "reflect" - "strings" -) - -// Internal state for executing a Template. As we evaluate the struct, -// the data item descends into the fields associated with sections, etc. -// Parent is used to walk upwards to find variables higher in the tree. -type state struct { - parent *state // parent in hierarchy - data reflect.Value // the driver data for this section etc. - wr io.Writer // where to send output - buf [2]bytes.Buffer // alternating buffers used when chaining formatters -} - -func (parent *state) clone(data reflect.Value) *state { - return &state{parent: parent, data: data, wr: parent.wr} -} - -// Evaluate interfaces and pointers looking for a value that can look up the name, via a -// struct field, method, or map key, and return the result of the lookup. -func (t *Template) lookup(st *state, v reflect.Value, name string) reflect.Value { - for v.IsValid() { - typ := v.Type() - if n := v.Type().NumMethod(); n > 0 { - for i := 0; i < n; i++ { - m := typ.Method(i) - mtyp := m.Type - if m.Name == name && mtyp.NumIn() == 1 && mtyp.NumOut() == 1 { - if !isExported(name) { - t.execError(st, t.linenum, "name not exported: %s in type %s", name, st.data.Type()) - } - return v.Method(i).Call(nil)[0] - } - } - } - switch av := v; av.Kind() { - case reflect.Ptr: - v = av.Elem() - case reflect.Interface: - v = av.Elem() - case reflect.Struct: - if !isExported(name) { - t.execError(st, t.linenum, "name not exported: %s in type %s", name, st.data.Type()) - } - return av.FieldByName(name) - case reflect.Map: - if v := av.MapIndex(reflect.ValueOf(name)); v.IsValid() { - return v - } - return reflect.Zero(typ.Elem()) - default: - return reflect.Value{} - } - } - return v -} - -// indirectPtr returns the item numLevels levels of indirection below the value. -// It is forgiving: if the value is not a pointer, it returns it rather than giving -// an error. If the pointer is nil, it is returned as is. -func indirectPtr(v reflect.Value, numLevels int) reflect.Value { - for i := numLevels; v.IsValid() && i > 0; i++ { - if p := v; p.Kind() == reflect.Ptr { - if p.IsNil() { - return v - } - v = p.Elem() - } else { - break - } - } - return v -} - -// Walk v through pointers and interfaces, extracting the elements within. -func indirect(v reflect.Value) reflect.Value { -loop: - for v.IsValid() { - switch av := v; av.Kind() { - case reflect.Ptr: - v = av.Elem() - case reflect.Interface: - v = av.Elem() - default: - break loop - } - } - return v -} - -// If the data for this template is a struct, find the named variable. -// Names of the form a.b.c are walked down the data tree. -// The special name "@" (the "cursor") denotes the current data. -// The value coming in (st.data) might need indirecting to reach -// a struct while the return value is not indirected - that is, -// it represents the actual named field. Leading stars indicate -// levels of indirection to be applied to the value. -func (t *Template) findVar(st *state, s string) reflect.Value { - data := st.data - flattenedName := strings.TrimLeft(s, "*") - numStars := len(s) - len(flattenedName) - s = flattenedName - if s == "@" { - return indirectPtr(data, numStars) - } - for _, elem := range strings.Split(s, ".") { - // Look up field; data must be a struct or map. - data = t.lookup(st, data, elem) - if !data.IsValid() { - return reflect.Value{} - } - } - return indirectPtr(data, numStars) -} - -// Is there no data to look at? -func empty(v reflect.Value) bool { - v = indirect(v) - if !v.IsValid() { - return true - } - switch v.Kind() { - case reflect.Bool: - return v.Bool() == false - case reflect.String: - return v.String() == "" - case reflect.Struct: - return false - case reflect.Map: - return false - case reflect.Array: - return v.Len() == 0 - case reflect.Slice: - return v.Len() == 0 - } - return false -} - -// Look up a variable or method, up through the parent if necessary. -func (t *Template) varValue(name string, st *state) reflect.Value { - field := t.findVar(st, name) - if !field.IsValid() { - if st.parent == nil { - t.execError(st, t.linenum, "name not found: %s in type %s", name, st.data.Type()) - } - return t.varValue(name, st.parent) - } - return field -} - -func (t *Template) format(wr io.Writer, fmt string, val []interface{}, v *variableElement, st *state) { - fn := t.formatter(fmt) - if fn == nil { - t.execError(st, v.linenum, "missing formatter %s for variable", fmt) - } - fn(wr, fmt, val...) -} - -// Evaluate a variable, looking up through the parent if necessary. -// If it has a formatter attached ({var|formatter}) run that too. -func (t *Template) writeVariable(v *variableElement, st *state) { - // Resolve field names - val := make([]interface{}, len(v.args)) - for i, arg := range v.args { - if name, ok := arg.(fieldName); ok { - val[i] = t.varValue(string(name), st).Interface() - } else { - val[i] = arg - } - } - for i, fmt := range v.fmts[:len(v.fmts)-1] { - b := &st.buf[i&1] - b.Reset() - t.format(b, fmt, val, v, st) - val = val[0:1] - val[0] = b.Bytes() - } - t.format(st.wr, v.fmts[len(v.fmts)-1], val, v, st) -} - -// Execute element i. Return next index to execute. -func (t *Template) executeElement(i int, st *state) int { - switch elem := t.elems[i].(type) { - case *textElement: - st.wr.Write(elem.text) - return i + 1 - case *literalElement: - st.wr.Write(elem.text) - return i + 1 - case *variableElement: - t.writeVariable(elem, st) - return i + 1 - case *sectionElement: - t.executeSection(elem, st) - return elem.end - case *repeatedElement: - t.executeRepeated(elem, st) - return elem.end - } - e := t.elems[i] - t.execError(st, 0, "internal error: bad directive in execute: %v %T\n", reflect.ValueOf(e).Interface(), e) - return 0 -} - -// Execute the template. -func (t *Template) execute(start, end int, st *state) { - for i := start; i < end; { - i = t.executeElement(i, st) - } -} - -// Execute a .section -func (t *Template) executeSection(s *sectionElement, st *state) { - // Find driver data for this section. It must be in the current struct. - field := t.varValue(s.field, st) - if !field.IsValid() { - t.execError(st, s.linenum, ".section: cannot find field %s in %s", s.field, st.data.Type()) - } - st = st.clone(field) - start, end := s.start, s.or - if !empty(field) { - // Execute the normal block. - if end < 0 { - end = s.end - } - } else { - // Execute the .or block. If it's missing, do nothing. - start, end = s.or, s.end - if start < 0 { - return - } - } - for i := start; i < end; { - i = t.executeElement(i, st) - } -} - -// Return the result of calling the Iter method on v, or nil. -func iter(v reflect.Value) reflect.Value { - for j := 0; j < v.Type().NumMethod(); j++ { - mth := v.Type().Method(j) - fv := v.Method(j) - ft := fv.Type() - // TODO(rsc): NumIn() should return 0 here, because ft is from a curried FuncValue. - if mth.Name != "Iter" || ft.NumIn() != 1 || ft.NumOut() != 1 { - continue - } - ct := ft.Out(0) - if ct.Kind() != reflect.Chan || - ct.ChanDir()&reflect.RecvDir == 0 { - continue - } - return fv.Call(nil)[0] - } - return reflect.Value{} -} - -// Execute a .repeated section -func (t *Template) executeRepeated(r *repeatedElement, st *state) { - // Find driver data for this section. It must be in the current struct. - field := t.varValue(r.field, st) - if !field.IsValid() { - t.execError(st, r.linenum, ".repeated: cannot find field %s in %s", r.field, st.data.Type()) - } - field = indirect(field) - - start, end := r.start, r.or - if end < 0 { - end = r.end - } - if r.altstart >= 0 { - end = r.altstart - } - first := true - - // Code common to all the loops. - loopBody := func(newst *state) { - // .alternates between elements - if !first && r.altstart >= 0 { - for i := r.altstart; i < r.altend; { - i = t.executeElement(i, newst) - } - } - first = false - for i := start; i < end; { - i = t.executeElement(i, newst) - } - } - - if array := field; array.Kind() == reflect.Array || array.Kind() == reflect.Slice { - for j := 0; j < array.Len(); j++ { - loopBody(st.clone(array.Index(j))) - } - } else if m := field; m.Kind() == reflect.Map { - for _, key := range m.MapKeys() { - loopBody(st.clone(m.MapIndex(key))) - } - } else if ch := iter(field); ch.IsValid() { - for { - e, ok := ch.Recv() - if !ok { - break - } - loopBody(st.clone(e)) - } - } else { - t.execError(st, r.linenum, ".repeated: cannot repeat %s (type %s)", - r.field, field.Type()) - } - - if first { - // Empty. Execute the .or block, once. If it's missing, do nothing. - start, end := r.or, r.end - if start >= 0 { - newst := st.clone(field) - for i := start; i < end; { - i = t.executeElement(i, newst) - } - } - return - } -} - -// A valid delimiter must contain no space and be non-empty. -func validDelim(d []byte) bool { - if len(d) == 0 { - return false - } - for _, c := range d { - if isSpace(c) { - return false - } - } - return true -} |