Centering alignments in equations

Question

I have a very long set of equations that I put in an array. They must be aligned as

\begin{array}{lclc}
 A     & Long expression              &  \text{\hspace{.5cm}}   & Long expression \\
.
.
.
Z  & Long expression              &  \text{\hspace{.5cm}}   & Long expression \\
\end{array}

This is for give you an idea of how long the expression can be. Moreover the second and fourth component must be centered. I would like to use align because it allows for page breaks of the equations in case they are too long, but if I use them, then the second and fourth components of the align are not centered anymore. How can I have a structure as follows:

\begin{align}
 A     & Long centered expression              &  \text{\hspace{.5cm}}   & Long centered expression \\
.
.
.
Z  & Long centered expression              &  \text{\hspace{.5cm}}   & Long centered expression \\
\end{align}

I need the equations to be numbered, centered and with the possibility of breaking in multiple pages if they are too long.

EDIT

I add an example:

\[
\begin{array}{lclc}
 A     & This is a very long expression              &  \text{\hspace{.5cm}}   & Also this is a long expression \\
 B     & Normal             &  \text{\hspace{.5cm}}   & Something \\
Z  & Short              &  \text{\hspace{.5cm}}   & This is even longer expression of before \\
\end{array}
\]

If you try it on a TeX file the second and the fourth columns are centered with respect to their content. If I have a very long expression, then if I use array, it is possible that the equations do not fit well in the page because it cannot be broken in multiple pages. So I was thinking of using align with \allowpagebreaks[1]. But if I use

\[
\begin{align}
 A     & This is a very long expression              &  \text{\hspace{.5cm}}   & Also this is a long expression \\
 B     & Normal             &  \text{\hspace{.5cm}}   & Something \\
Z  & Short              &  \text{\hspace{.5cm}}   & This is even longer expression of before \\
\end{align}
\]

You see that the alignments of the second and fourth columns are with respect to the & symbol, and not centered with respect to their content.

I hope that the example clarifies my question

Answer 1

Note that you can not have align inside \[ The simplest and most common way is to add alignment points within the expression so they alig towards the alignment point rather tahn appear to be flush left or right. I added | here to make the alignment visible in teh output but that is not needed. Note that the example text is already too wide to fit in a standard text block even if I remove the .5cm spacing (there is no need for \hspace to be inside \text) If you have a much wider text block or your real expressions are smaller you could of course re-add spacing, although align already adds space between each expression (that is between each pair of columns)

\documentclass[a4paper]{article}
\usepackage{amsmath}
\begin{document}
\begin{align}
 A     && This isa very&|long expression      & Also this &|is a long expression \
 B     &&  Normal&|              & Some&|thing \
Z  &&       Short&|              & This is even &|longer expression of before
\end{align}
\end{document}

Answer 2

You can do it with alignat and eqparbox. The label for the boxes is automatically generated for each align-lcc display.

Dont' add a trailing \\, as is mandatory for align and friends.

\documentclass{article}
\usepackage{amsmath,eqparbox}
\ExplSyntaxOn
\NewDocumentEnvironment{align-lcc}{b}
 {
  \mininno_align_lcc:n { #1 }
 }
 {}
\seq_new:N \l__mininno_align_body_seq
\seq_new:N \l__mininno_align_row_seq
\tl_new:N \l__mininno_align_body_tl
\int_new:N \g__mininno_align_rows_int
\cs_new_protected:Nn \mininno_align_lcc:n
 {
  \int_gincr:N \g__mininno_align_rows_int
  \tl_clear:N \l__mininno_align_body_tl
  \seq_set_split:Nnn \l__mininno_align_body_seq { \ } { #1 }
  \seq_map_indexed_function:NN \l__mininno_align_body_seq __mininno_align_row:nn
  \begin{alignat}{3}
  \tl_use:N \l__mininno_align_body_tl
  \end{alignat}
 }
\cs_new_protected:Nn __mininno_align_row:nn
 {
  \seq_set_split:Nnn \l__mininno_align_row_seq { & } { #2 }
  \tl_put_right:Nx \l__mininno_align_body_tl { \seq_item:Nn \l__mininno_align_row_seq { 1 } }
  \tl_put_right:Nx \l__mininno_align_body_tl
   {
    __mininno_align_cell:nn {A}{\seq_item:Nn \l__mininno_align_row_seq { 2 }}
   }
  \tl_put_right:Nx \l__mininno_align_body_tl
   {
    __mininno_align_cell:nn {B}{\seq_item:Nn \l__mininno_align_row_seq { 3 }}
   }
  \int_compare:nF { #1 == \seq_count:N \l__mininno_align_body_seq }
   { \tl_put_right:Nn \l__mininno_align_body_tl { \ } }
 }
\cs_new_protected:Nn __mininno_align_cell:nn
 {
  &\quad&
  \eqmakebox[#1-\int_to_arabic:n {\g__mininno_align_rows_int}][c]{$\displaystyle#2$}
 }
\ExplSyntaxOff
\begin{document}
\begin{align-lcc}
 A & This is a very long expression & Also this is a long expression \
 B & Normal                         & Something \
 Z & Short                          & This is even longer expression of before
\end{align-lcc}
\end{document}

The idea is to split the input at \\, then each row at & and fill in using \eqmakebox.