mirror of https://github.com/texmacs/doc.git
187 lines
10 KiB
Tcl
187 lines
10 KiB
Tcl
<TeXmacs|1.99.1>
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<style|<tuple|tmdoc|english>>
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<\body>
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<tmdoc-title|Fundamental tree modification routines>
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From an internal point of view, all modifications to the <TeXmacs> edit
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tree are decomposed into atomic modifications of eight different types. In
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this section, we describe the <scheme> interface to these fundamental
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modification routines. Even though it is usually more convenient to use
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higher level modification routines, as described in the <hlink|next
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section|edit-modify.en.tm>, the fundamental tree modification routines may
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occasionally be useful as well.
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It should be emphasized that the fundamental tree modification routines are
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<em|not> checked for their correctness. It is the responsability of the
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user to verify that the operations are valid and that they lead to a
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correct new edit tree. Although it is sometimes possible to leave the edit
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tree in a temporarily incorrect or ``unsimplified'' state (for instance, by
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allowing subtrees of the form <rigid|<scm|(concat "")>>), this practice is
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not generally recommended, and may lead to severe bugs.
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<\explain>
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<scm|(tree-assign! <scm-arg|var> <scm-arg|new-value>)><explain-synopsis|tree
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assignment>
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<|explain>
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On input, we have a <scheme> variable <scm-arg|var> of type
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<verbatim|tree> and <scm-arg|new-value> of type <verbatim|content>. The
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macro replaces the tree by <scm-arg|new-value> and updates <scm-arg|var>
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accordingly. The new tree value of <scm-arg|var> is returned.
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</explain>
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<\explain>
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<scm|(tree-insert! <scm-arg|var> <scm-arg|pos>
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<scm-arg|ins>)><explain-synopsis|insertion of new nodes or characters>
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<|explain>
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The first parameter <scm-arg|var> is a <scheme> variable of type
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<verbatim|tree>. If <scm-arg|var> is a compound tree, then <scm-arg|ins>
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should be a list <math|u<rsub|0>,\<ldots\>,u<rsub|l-1>> of new children
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of type <verbatim|content>. In that case, the routine inserts
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<math|u<rsub|0>,\<ldots\>,u<rsub|l-1>> into the children of
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<scm-arg|var>, at position <scm-arg|pos> (see figure
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<reference|insert-remove-fig>). If <scm-arg|var> is a string tree, then
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<scm-arg|ins> should be of string content type, and the string
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<scm-arg|ins> is inserted into <scm-arg|var> at position <scm-arg|pos>.
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The variable <scm-arg|var> is updated with the result of the insertion
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and the result is returned.
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</explain>
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<\explain>
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<scm|(tree-remove! <scm-arg|var> <scm-arg|pos>
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<scm-arg|nr>)><explain-synopsis|removal of nodes or characters>
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<|explain>
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The first parameter <scm-arg|var> is a <scheme> variable of type
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<verbatim|tree>. If <scm-arg|var> is a compound tree, then <scm-arg|nr>
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of its children are removed, starting at position <scm-arg|pos> (see
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figure <reference|insert-remove-fig>). If <scm-arg|var> is a string tree,
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then <scm-arg|nr> characters are removed, starting at position
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<scm-arg|pos>. The variable <scm-arg|var> is updated with the result of
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the removal and the result is returned.
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</explain>
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<\big-figure>
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<\equation*>
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<tabular*|<tformat|<table|<row|<cell|<tabular*|<tformat|<cwith|1|1|3|3|cell-valign|c>|<table|<row|<cell|<tree|t|t<rsub|0>|\<cdots\>|t<rsub|n-1>>>|<cell|>|<cell|\<longrightarrowlim\><rsup|insert<around|(|t,i,u|)>>>|<cell|>|<cell|<tree|t|t<rsub|0>|\<cdots\>|t<rsub|i-1>|u<rsub|0>|\<cdots\>|u<rsub|l-1>|t<rsub|i>|\<cdots\>|t<rsub|n-1>>>>>>>>>|<row|<cell|>>|<row|<cell|<tabular*|<tformat|<cwith|1|1|3|3|cell-valign|c>|<table|<row|<cell|<tree|t|t<rsub|0>|\<cdots\>|t<rsub|n-1>>>|<cell|>|<cell|\<longrightarrowlim\><rsup|remove<around|(|t,i,l|)>>>|<cell|>|<cell|<tree|t|t<rsub|0>|\<cdots\>|t<rsub|i-1>|t<rsub|i+l>|\<cdots\>|t<rsub|n-1>>>>>>>>>>>>
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</equation*>
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\;
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<|big-figure>
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<label|insert-remove-fig>Illustration of the operations
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<scm|(tree-insert! t i u)> and <scm|(tree-remove! t i l)>. If <scm|u> has
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length<nbsp><scm|l>, then we notice that <scm|(tree-remove! t i l)> undos
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the insertion <scm|(tree-insert! t i u)>.
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</big-figure>
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\;
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<\explain>
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<scm|(tree-split! <scm-arg|var> <scm-arg|pos>
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<scm-arg|at>)><explain-synopsis|split the children into two parts>
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<|explain>
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The first parameter <scm-arg|var> is a <scheme> variable of type
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<verbatim|tree>. The macro is used to split the child <math|u> of
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<scm-arg|var> at position <scm-arg|pos> into two parts. If <math|u> is a
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compound tree, then the first part consists of the first <scm-arg|at>
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children and the second part of the remaining ones. Both parts carry the
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same label as <math|u> and <math|u> is replaced by the two parts inside
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<scm-arg|var> (see figure <reference|split-join-fig>). If <math|u> is
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string tree, then it is rather split into two strings at position
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<scm-arg|at>. The variable <scm-arg|var> is updated with the result of
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the split command and the result is returned.
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</explain>
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<\explain>
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<scm|(tree-join! <scm-arg|var> <scm-arg|pos>)><explain-synopsis|join two
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adjacent nodes>
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<|explain>
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The first parameter <scm-arg|var> is a <scheme> variable of type
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<verbatim|tree>. This macro is used to join the child <math|u> of
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<scm-arg|var> at position <scm-arg|pos> with the child <math|v> at
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position <scm-arg|pos>+1. If <math|u> and <math|v> are trees, then they
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are removed from <scm-arg|var> and replaced by a single tree which has
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the same label as <math|u> and whose children are those of <math|u>,
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followed by the children of <math|v> (see figure
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<reference|split-join-fig>). If <math|u> and <math|v> are strings, then
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they are replaced by their concatenation. The variable <scm-arg|var> is
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updated with the result of the join command and the result is returned.
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</explain>
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<\big-figure>
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<\equation*>
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<tabular*|<tformat|<table|<row|<cell|<tabular*|<tformat|<cwith|1|1|3|3|cell-valign|c>|<table|<row|<cell|<tree|t|t<rsub|0>|\<cdots\>|<resize|<tree|t<rsub|i>|t<rsub|i,0>|\<cdots\>|t<rsub|i,k-1>>|<plus|1l|1fn>||<minus|1r|1fn>|>|\<cdots\>|t<rsub|n-1>>>|<cell|>|<cell|\<longrightarrowlim\><rsup|split<around|(|t,i,j|)>>>|<cell|>|<cell|<tree|t|t<rsub|0>|\<cdots\>|<resize|<tree|t<rsub|i>|t<rsub|i,0>|\<cdots\>|t<rsub|i,j-1>>|<plus|1l|1fn>|||>|<resize|<tree|t<rsub|i>|t<rsub|i,j>|\<cdots\>|t<rsub|i,k-1>>|||<minus|1r|1fn>|>|\<cdots\>|t<rsub|n-1>>>>>>><space|1em><space|1em>>>|<row|<cell|>>|<row|<cell|<tabular*|<tformat|<cwith|1|1|3|3|cell-valign|c>|<table|<row|<cell|<tree|t|t<rsub|0>|\<cdots\>|<resize|<tree|t<rsub|i>|t<rsub|i,0>|\<cdots\>|t<rsub|i,j-1>>|<plus|1l|2fn>|||>|<resize|<tree|t<rsub|i+1>|t<rsub|i+1,j>|\<cdots\>|t<rsub|i+1,k-1>>|||<minus|1r|2fn>|>|\<cdots\>|t<rsub|n-1>>>|<cell|>|<cell|\<longrightarrowlim\><rsup|join<around|(|t,i|)>>>|<cell|>|<cell|<tree|t|t<rsub|0>|\<cdots\>|<resize|<tree|t<rsub|i>|t<rsub|i,0>|\<cdots\>|t<rsub|i,j-1>|t<rsub|i+1,0>|\<cdots\>|t<rsub|i+1,k-1>>|<plus|1l|4fn>||<minus|1r|4fn>|>|\<cdots\>|t<rsub|n-1>>>>>>>>>>>>
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</equation*>
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\;
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<|big-figure>
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<label|split-join-fig>Illustration of the operations <scm|(tree-split! t
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i j)> and <scm|(tree-join! t i)>. Notice that <scm|(tree-join! t i)>
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undos <scm|(tree-split! t i j)>.
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</big-figure>
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<\explain>
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<scm|(tree-assign-node! <scm-arg|var>
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<scm-arg|lab>)><explain-synopsis|assign the label of a tree>
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<|explain>
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This macro replaces the label of a compound tree stored in a <scheme>
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variable <scm-arg|var> by a new value <scm-arg|lab>. The result of the
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substitution is returned.
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</explain>
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<\explain>
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<scm|(tree-insert-node! <scm-arg|var> <scm-arg|pos>
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<scm-arg|ins>)><explain-synopsis|insert the tree as a child of another
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one>
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<|explain>
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Given a <scheme> variable <scm-arg|var>, containing a tree, and a content
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tree <scm-arg|ins>, this macro replaces <scm-arg|var> by <scm-arg|ins>,
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with <scm-arg|var> inserted as a new child of <scm-arg|ins> at position
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<scm-arg|pos> (see figure <reference|insert-remove-node-fig>). The result
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of the insertion is returned.
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</explain>
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<\explain>
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<scm|(tree-remove-node! <scm-arg|var>
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<scm-arg|pos>)><explain-synopsis|replace a tree by a child>
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<|explain>
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Given a <scheme> variable <scm-arg|var>, containing a compound tree, this
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macro replaces <scm-arg|var> by its child at position <scm-arg|pos> (see
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figure <reference|insert-remove-node-fig>). The value of this child is
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returned.
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</explain>
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<\big-figure>
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<\equation*>
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<tabular*|<tformat|<table|<row|<cell|<tabular*|<tformat|<cwith|1|1|3|3|cell-valign|c>|<cwith|1|1|1|1|cell-valign|c>|<table|<row|<cell|t>|<cell|>|<cell|\<longrightarrowlim\><rsup|insert-node<around|(|t,i,u|)>>>|<cell|>|<cell|<tree|u|u<rsub|0>|\<cdots\>|u<rsub|i-1>|t|u<rsub|i>|\<cdots\>|u<rsub|n-1>>>>>>>>>|<row|<cell|>>|<row|<cell|<tabular*|<tformat|<cwith|1|1|3|3|cell-valign|c>|<cwith|1|1|5|5|cell-valign|c>|<table|<row|<cell|<tree|t|t<rsub|0>|\<cdots\>|t<rsub|n-1>>>|<cell|>|<cell|\<longrightarrowlim\><rsup|remove-node<around|(|t,i|)>>>|<cell|>|<cell|t<rsub|i>>>>>>>>>>>
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</equation*>
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\;
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<|big-figure>
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<label|insert-remove-node-fig>Illustration of the operations
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<scm|(tree-insert-node! t i u)> and <scm|(tree-remove-node! t i)>. Notice
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that the second operation undoes the first one.
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</big-figure>
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<\remark>
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Each of the macros <scm|tree-assign!>, <scm|tree-insert!>, <abbr|etc.>
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has a functional counterpart <verbatim|<scm|tree-assign>>,
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<verbatim|<scm|tree-insert>>, etc. The first parameter of these
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counterparts can be an arbitrary ``l-<no-break>value'' and does not have
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to be a scheme variable. However, in the case when a <scheme> variable is
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passed as the first parameter, these variants do not necessarily update
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its contents with the return value.
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</remark>
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<tmdoc-copyright|2005|Joris van der Hoeven>
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<tmdoc-license|Permission is granted to copy, distribute and/or modify this
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document under the terms of the GNU Free Documentation License, Version 1.1
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or any later version published by the Free Software Foundation; with no
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Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
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Texts. A copy of the license is included in the section entitled "GNU Free
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Documentation License".>
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</body>
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<initial|<\collection>
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</collection>> |