mirror of git://gcc.gnu.org/git/gcc.git
92 lines
3.5 KiB
Go
92 lines
3.5 KiB
Go
// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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/*
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Package template implements data-driven templates for generating textual
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output such as HTML.
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Templates are executed by applying them to a data structure.
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Annotations in the template refer to elements of the data
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structure (typically a field of a struct or a key in a map)
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to control execution and derive values to be displayed.
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The template walks the structure as it executes and the
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"cursor" @ represents the value at the current location
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in the structure.
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Data items may be values or pointers; the interface hides the
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indirection.
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In the following, 'Field' is one of several things, according to the data.
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- The name of a field of a struct (result = data.Field),
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- The value stored in a map under that key (result = data["Field"]), or
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- The result of invoking a niladic single-valued method with that name
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(result = data.Field())
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If Field is a struct field or method name, it must be an exported
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(capitalized) name.
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Major constructs ({} are the default delimiters for template actions;
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[] are the notation in this comment for optional elements):
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{# comment }
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A one-line comment.
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{.section field} XXX [ {.or} YYY ] {.end}
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Set @ to the value of the field. It may be an explicit @
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to stay at the same point in the data. If the field is nil
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or empty, execute YYY; otherwise execute XXX.
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{.repeated section field} XXX [ {.alternates with} ZZZ ] [ {.or} YYY ] {.end}
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Like .section, but field must be an array or slice. XXX
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is executed for each element. If the array is nil or empty,
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YYY is executed instead. If the {.alternates with} marker
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is present, ZZZ is executed between iterations of XXX.
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{field}
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{field1 field2 ...}
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{field|formatter}
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{field1 field2...|formatter}
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{field|formatter1|formatter2}
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Insert the value of the fields into the output. Each field is
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first looked for in the cursor, as in .section and .repeated.
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If it is not found, the search continues in outer sections
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until the top level is reached.
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If the field value is a pointer, leading asterisks indicate
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that the value to be inserted should be evaluated through the
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pointer. For example, if x.p is of type *int, {x.p} will
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insert the value of the pointer but {*x.p} will insert the
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value of the underlying integer. If the value is nil or not a
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pointer, asterisks have no effect.
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If a formatter is specified, it must be named in the formatter
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map passed to the template set up routines or in the default
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set ("html","str","") and is used to process the data for
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output. The formatter function has signature
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func(wr io.Writer, formatter string, data ...interface{})
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where wr is the destination for output, data holds the field
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values at the instantiation, and formatter is its name at
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the invocation site. The default formatter just concatenates
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the string representations of the fields.
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Multiple formatters separated by the pipeline character | are
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executed sequentially, with each formatter receiving the bytes
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emitted by the one to its left.
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As well as field names, one may use literals with Go syntax.
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Integer, floating-point, and string literals are supported.
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Raw strings may not span newlines.
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The delimiter strings get their default value, "{" and "}", from
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JSON-template. They may be set to any non-empty, space-free
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string using the SetDelims method. Their value can be printed
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in the output using {.meta-left} and {.meta-right}.
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*/
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package template
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