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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [old/] [template/] [execute.go] - Blame information for rev 854

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// 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
}

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Subversion Repositories openrisc

[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libgo/] [go/] [old/] [template/] [execute.go] - Blame information for rev 854

Line No.	Rev	Author	Line
1	747	jeremybenn	`// Copyright 2009 The Go Authors. All rights reserved.`
2			`// Use of this source code is governed by a BSD-style`
3			`// license that can be found in the LICENSE file.`
4
5			`// Code to execute a parsed template.`
6
7			`package template`
8
9			`import (`
10			`"bytes"`
11			`"io"`
12			`"reflect"`
13			`"strings"`
14			`)`
15
16			`// Internal state for executing a Template. As we evaluate the struct,`
17			`// the data item descends into the fields associated with sections, etc.`
18			`// Parent is used to walk upwards to find variables higher in the tree.`
19			`type state struct {`
20			`parent *state // parent in hierarchy`
21			`data reflect.Value // the driver data for this section etc.`
22			`wr io.Writer // where to send output`
23			`buf [2]bytes.Buffer // alternating buffers used when chaining formatters`
24			`}`
25
26			`func (parent state) clone(data reflect.Value) state {`
27			`return &state{parent: parent, data: data, wr: parent.wr}`
28			`}`
29
30			`// Evaluate interfaces and pointers looking for a value that can look up the name, via a`
31			`// struct field, method, or map key, and return the result of the lookup.`
32			`func (t Template) lookup(st state, v reflect.Value, name string) reflect.Value {`
33			`for v.IsValid() {`
34			`typ := v.Type()`
35			`if n := v.Type().NumMethod(); n > 0 {`
36			`for i := 0; i < n; i++ {`
37			`m := typ.Method(i)`
38			`mtyp := m.Type`
39			`if m.Name == name && mtyp.NumIn() == 1 && mtyp.NumOut() == 1 {`
40			`if !isExported(name) {`
41			`t.execError(st, t.linenum, "name not exported: %s in type %s", name, st.data.Type())`
42			`}`
43			`return v.Method(i).Call(nil)[0]`
44			`}`
45			`}`
46			`}`
47			`switch av := v; av.Kind() {`
48			`case reflect.Ptr:`
49			`v = av.Elem()`
50			`case reflect.Interface:`
51			`v = av.Elem()`
52			`case reflect.Struct:`
53			`if !isExported(name) {`
54			`t.execError(st, t.linenum, "name not exported: %s in type %s", name, st.data.Type())`
55			`}`
56			`return av.FieldByName(name)`
57			`case reflect.Map:`
58			`if v := av.MapIndex(reflect.ValueOf(name)); v.IsValid() {`
59			`return v`
60			`}`
61			`return reflect.Zero(typ.Elem())`
62			`default:`
63			`return reflect.Value{}`
64			`}`
65			`}`
66			`return v`
67			`}`
68
69			`// indirectPtr returns the item numLevels levels of indirection below the value.`
70			`// It is forgiving: if the value is not a pointer, it returns it rather than giving`
71			`// an error. If the pointer is nil, it is returned as is.`
72			`func indirectPtr(v reflect.Value, numLevels int) reflect.Value {`
73			`for i := numLevels; v.IsValid() && i > 0; i++ {`
74			`if p := v; p.Kind() == reflect.Ptr {`
75			`if p.IsNil() {`
76			`return v`
77			`}`
78			`v = p.Elem()`
79			`} else {`
80			`break`
81			`}`
82			`}`
83			`return v`
84			`}`
85
86			`// Walk v through pointers and interfaces, extracting the elements within.`
87			`func indirect(v reflect.Value) reflect.Value {`
88			`loop:`
89			`for v.IsValid() {`
90			`switch av := v; av.Kind() {`
91			`case reflect.Ptr:`
92			`v = av.Elem()`
93			`case reflect.Interface:`
94			`v = av.Elem()`
95			`default:`
96			`break loop`
97			`}`
98			`}`
99			`return v`
100			`}`
101
102			`// If the data for this template is a struct, find the named variable.`
103			`// Names of the form a.b.c are walked down the data tree.`
104			`// The special name "@" (the "cursor") denotes the current data.`
105			`// The value coming in (st.data) might need indirecting to reach`
106			`// a struct while the return value is not indirected - that is,`
107			`// it represents the actual named field. Leading stars indicate`
108			`// levels of indirection to be applied to the value.`
109			`func (t Template) findVar(st state, s string) reflect.Value {`
110			`data := st.data`
111			`flattenedName := strings.TrimLeft(s, "*")`
112			`numStars := len(s) - len(flattenedName)`
113			`s = flattenedName`
114			`if s == "@" {`
115			`return indirectPtr(data, numStars)`
116			`}`
117			`for _, elem := range strings.Split(s, ".") {`
118			`// Look up field; data must be a struct or map.`
119			`data = t.lookup(st, data, elem)`
120			`if !data.IsValid() {`
121			`return reflect.Value{}`
122			`}`
123			`}`
124			`return indirectPtr(data, numStars)`
125			`}`
126
127			`// Is there no data to look at?`
128			`func empty(v reflect.Value) bool {`
129			`v = indirect(v)`
130			`if !v.IsValid() {`
131			`return true`
132			`}`
133			`switch v.Kind() {`
134			`case reflect.Bool:`
135			`return v.Bool() == false`
136			`case reflect.String:`
137			`return v.String() == ""`
138			`case reflect.Struct:`
139			`return false`
140			`case reflect.Map:`
141			`return false`
142			`case reflect.Array:`
143			`return v.Len() == 0`
144			`case reflect.Slice:`
145			`return v.Len() == 0`
146			`}`
147			`return false`
148			`}`
149
150			`// Look up a variable or method, up through the parent if necessary.`
151			`func (t Template) varValue(name string, st state) reflect.Value {`
152			`field := t.findVar(st, name)`
153			`if !field.IsValid() {`
154			`if st.parent == nil {`
155			`t.execError(st, t.linenum, "name not found: %s in type %s", name, st.data.Type())`
156			`}`
157			`return t.varValue(name, st.parent)`
158			`}`
159			`return field`
160			`}`
161
162			`func (t Template) format(wr io.Writer, fmt string, val []interface{}, v variableElement, st *state) {`
163			`fn := t.formatter(fmt)`
164			`if fn == nil {`
165			`t.execError(st, v.linenum, "missing formatter %s for variable", fmt)`
166			`}`
167			`fn(wr, fmt, val...)`
168			`}`
169
170			`// Evaluate a variable, looking up through the parent if necessary.`
171			`// If it has a formatter attached ({var\|formatter}) run that too.`
172			`func (t Template) writeVariable(v variableElement, st *state) {`
173			`// Resolve field names`
174			`val := make([]interface{}, len(v.args))`
175			`for i, arg := range v.args {`
176			`if name, ok := arg.(fieldName); ok {`
177			`val[i] = t.varValue(string(name), st).Interface()`
178			`} else {`
179			`val[i] = arg`
180			`}`
181			`}`
182			`for i, fmt := range v.fmts[:len(v.fmts)-1] {`
183			`b := &st.buf[i&1]`
184			`b.Reset()`
185			`t.format(b, fmt, val, v, st)`
186			`val = val[0:1]`
187			`val[0] = b.Bytes()`
188			`}`
189			`t.format(st.wr, v.fmts[len(v.fmts)-1], val, v, st)`
190			`}`
191
192			`// Execute element i. Return next index to execute.`
193			`func (t Template) executeElement(i int, st state) int {`
194			`switch elem := t.elems[i].(type) {`
195			`case *textElement:`
196			`st.wr.Write(elem.text)`
197			`return i + 1`
198			`case *literalElement:`
199			`st.wr.Write(elem.text)`
200			`return i + 1`
201			`case *variableElement:`
202			`t.writeVariable(elem, st)`
203			`return i + 1`
204			`case *sectionElement:`
205			`t.executeSection(elem, st)`
206			`return elem.end`
207			`case *repeatedElement:`
208			`t.executeRepeated(elem, st)`
209			`return elem.end`
210			`}`
211			`e := t.elems[i]`
212			`t.execError(st, 0, "internal error: bad directive in execute: %v %T\n", reflect.ValueOf(e).Interface(), e)`
213			`return 0`
214			`}`
215
216			`// Execute the template.`
217			`func (t Template) execute(start, end int, st state) {`
218			`for i := start; i < end; {`
219			`i = t.executeElement(i, st)`
220			`}`
221			`}`
222
223			`// Execute a .section`
224			`func (t Template) executeSection(s sectionElement, st *state) {`
225			`// Find driver data for this section. It must be in the current struct.`
226			`field := t.varValue(s.field, st)`
227			`if !field.IsValid() {`
228			`t.execError(st, s.linenum, ".section: cannot find field %s in %s", s.field, st.data.Type())`
229			`}`
230			`st = st.clone(field)`
231			`start, end := s.start, s.or`
232			`if !empty(field) {`
233			`// Execute the normal block.`
234			`if end < 0 {`
235			`end = s.end`
236			`}`
237			`} else {`
238			`// Execute the .or block. If it's missing, do nothing.`
239			`start, end = s.or, s.end`
240			`if start < 0 {`
241			`return`
242			`}`
243			`}`
244			`for i := start; i < end; {`
245			`i = t.executeElement(i, st)`
246			`}`
247			`}`
248
249			`// Return the result of calling the Iter method on v, or nil.`
250			`func iter(v reflect.Value) reflect.Value {`
251			`for j := 0; j < v.Type().NumMethod(); j++ {`
252			`mth := v.Type().Method(j)`
253			`fv := v.Method(j)`
254			`ft := fv.Type()`
255			`// TODO(rsc): NumIn() should return 0 here, because ft is from a curried FuncValue.`
256			`if mth.Name != "Iter" \|\| ft.NumIn() != 1 \|\| ft.NumOut() != 1 {`
257			`continue`
258			`}`
259			`ct := ft.Out(0)`
260			`if ct.Kind() != reflect.Chan \|\|`
261			`ct.ChanDir()&reflect.RecvDir == 0 {`
262			`continue`
263			`}`
264			`return fv.Call(nil)[0]`
265			`}`
266			`return reflect.Value{}`
267			`}`
268
269			`// Execute a .repeated section`
270			`func (t Template) executeRepeated(r repeatedElement, st *state) {`
271			`// Find driver data for this section. It must be in the current struct.`
272			`field := t.varValue(r.field, st)`
273			`if !field.IsValid() {`
274			`t.execError(st, r.linenum, ".repeated: cannot find field %s in %s", r.field, st.data.Type())`
275			`}`
276			`field = indirect(field)`
277
278			`start, end := r.start, r.or`
279			`if end < 0 {`
280			`end = r.end`
281			`}`
282			`if r.altstart >= 0 {`
283			`end = r.altstart`
284			`}`
285			`first := true`
286
287			`// Code common to all the loops.`
288			`loopBody := func(newst *state) {`
289			`// .alternates between elements`
290			`if !first && r.altstart >= 0 {`
291			`for i := r.altstart; i < r.altend; {`
292			`i = t.executeElement(i, newst)`
293			`}`
294			`}`
295			`first = false`
296			`for i := start; i < end; {`
297			`i = t.executeElement(i, newst)`
298			`}`
299			`}`
300
301			`if array := field; array.Kind() == reflect.Array \|\| array.Kind() == reflect.Slice {`
302			`for j := 0; j < array.Len(); j++ {`
303			`loopBody(st.clone(array.Index(j)))`
304			`}`
305			`} else if m := field; m.Kind() == reflect.Map {`
306			`for _, key := range m.MapKeys() {`
307			`loopBody(st.clone(m.MapIndex(key)))`
308			`}`
309			`} else if ch := iter(field); ch.IsValid() {`
310			`for {`
311			`e, ok := ch.Recv()`
312			`if !ok {`
313			`break`
314			`}`
315			`loopBody(st.clone(e))`
316			`}`
317			`} else {`
318			`t.execError(st, r.linenum, ".repeated: cannot repeat %s (type %s)",`
319			`r.field, field.Type())`
320			`}`
321
322			`if first {`
323			`// Empty. Execute the .or block, once. If it's missing, do nothing.`
324			`start, end := r.or, r.end`
325			`if start >= 0 {`
326			`newst := st.clone(field)`
327			`for i := start; i < end; {`
328			`i = t.executeElement(i, newst)`
329			`}`
330			`}`
331			`return`
332			`}`
333			`}`
334
335			`// A valid delimiter must contain no space and be non-empty.`
336			`func validDelim(d []byte) bool {`
337			`if len(d) == 0 {`
338			`return false`
339			`}`
340			`for _, c := range d {`
341			`if isSpace(c) {`
342			`return false`
343			`}`
344			`}`
345			`return true`
346			`}`