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Diffstat (limited to 'src/pkg/template/doc.go')
-rw-r--r-- | src/pkg/template/doc.go | 91 |
1 files changed, 91 insertions, 0 deletions
diff --git a/src/pkg/template/doc.go b/src/pkg/template/doc.go new file mode 100644 index 000000000..e778d801d --- /dev/null +++ b/src/pkg/template/doc.go @@ -0,0 +1,91 @@ +// 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. + +/* + Package template implements data-driven templates for generating textual + output such as HTML. + + Templates are executed by applying them to a data structure. + Annotations in the template refer to elements of the data + structure (typically a field of a struct or a key in a map) + to control execution and derive values to be displayed. + The template walks the structure as it executes and the + "cursor" @ represents the value at the current location + in the structure. + + Data items may be values or pointers; the interface hides the + indirection. + + In the following, 'Field' is one of several things, according to the data. + + - The name of a field of a struct (result = data.Field), + - The value stored in a map under that key (result = data["Field"]), or + - The result of invoking a niladic single-valued method with that name + (result = data.Field()) + + If Field is a struct field or method name, it must be an exported + (capitalized) name. + + Major constructs ({} are the default delimiters for template actions; + [] are the notation in this comment for optional elements): + + {# comment } + + A one-line comment. + + {.section field} XXX [ {.or} YYY ] {.end} + + Set @ to the value of the field. It may be an explicit @ + to stay at the same point in the data. If the field is nil + or empty, execute YYY; otherwise execute XXX. + + {.repeated section field} XXX [ {.alternates with} ZZZ ] [ {.or} YYY ] {.end} + + Like .section, but field must be an array or slice. XXX + is executed for each element. If the array is nil or empty, + YYY is executed instead. If the {.alternates with} marker + is present, ZZZ is executed between iterations of XXX. + + {field} + {field1 field2 ...} + {field|formatter} + {field1 field2...|formatter} + {field|formatter1|formatter2} + + Insert the value of the fields into the output. Each field is + first looked for in the cursor, as in .section and .repeated. + If it is not found, the search continues in outer sections + until the top level is reached. + + If the field value is a pointer, leading asterisks indicate + that the value to be inserted should be evaluated through the + pointer. For example, if x.p is of type *int, {x.p} will + insert the value of the pointer but {*x.p} will insert the + value of the underlying integer. If the value is nil or not a + pointer, asterisks have no effect. + + If a formatter is specified, it must be named in the formatter + map passed to the template set up routines or in the default + set ("html","str","") and is used to process the data for + output. The formatter function has signature + func(wr io.Writer, formatter string, data ...interface{}) + where wr is the destination for output, data holds the field + values at the instantiation, and formatter is its name at + the invocation site. The default formatter just concatenates + the string representations of the fields. + + Multiple formatters separated by the pipeline character | are + executed sequentially, with each formatter receiving the bytes + emitted by the one to its left. + + As well as field names, one may use literals with Go syntax. + Integer, floating-point, and string literals are supported. + Raw strings may not span newlines. + + The delimiter strings get their default value, "{" and "}", from + JSON-template. They may be set to any non-empty, space-free + string using the SetDelims method. Their value can be printed + in the output using {.meta-left} and {.meta-right}. +*/ +package template |