Initial prototype.

This commit introduces a new library, copilot-visualizer, that produces
a tikz diagram from a Copilot spec.

The library leverages the interpreter, so externs must contain enough
samples for the visualization to take place.

Co-authored-by: Frank Dedden <frank@systemf.dev>

Author: ivanperez-keera

CHANGELOG

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+2009
+BSD3 License terms
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions
+are met:
+
+Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+
+Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+
+Neither the name of the developers nor the names of its contributors
+may be used to endorse or promote products derived from this software
+without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

LICENSE

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+[![Build Status](https://travis-ci.com/Copilot-Language/copilot.svg?branch=master)](https://app.travis-ci.com/github/Copilot-Language/copilot)
+
+# Copilot: a stream DSL
+
+The visualizer, which draws Copilot specifications using different graphical
+formats.
+
+Copilot is a runtime verification framework written in Haskell. It allows the
+user to write programs in a simple but powerful way using a stream-based
+approach.
+
+Programs can be interpreted for testing (with the library copilot-interpreter),
+or translated C99 code to be incorporated in a project, or as a standalone
+application. The C99 backend ensures us that the output is constant in memory
+and time, making it suitable for systems with hard realtime requirements.
+
+## Installation
+
+Copilot-visualizer can be found on
+[Hackage](https://hackage.haskell.org/package/copilot-interpreter). It is
+typically only installed as part of the complete Copilot distribution. For
+installation instructions, please refer to the [Copilot
+website](https://copilot-language.github.io).
+
+## Further information
+
+For further information, install instructions and documentation, please visit
+the Copilot website:
+[https://copilot-language.github.io](https://copilot-language.github.io)
+
+## License
+
+Copilot is distributed under the BSD-3-Clause license, which can be found
+[here](https://raw.githubusercontent.com/Copilot-Language/copilot/master/copilot-interpreter/LICENSE).

README.md

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+import Distribution.Simple
+main = defaultMain

Setup.hs

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+cabal-version:       >=1.10
+name:                copilot-visualizer
+version:             4.2
+synopsis:            Visualizer for Copilot.
+description:
+  Visualizer for Copilot.
+  .
+  Copilot is a stream (i.e., infinite lists) domain-specific language (DSL) in
+  Haskell that compiles into embedded C. Copilot contains an interpreter,
+  multiple back-end compilers, and other verification tools.
+  .
+  A tutorial, examples, and other information are available at
+  <https://copilot-language.github.io>.
+
+author:              Ivan Perez, Frank Dedden
+license:             BSD3
+license-file:        LICENSE
+maintainer:          Ivan Perez <ivan.perezdominguez@nasa.gov>
+homepage:            https://copilot-language.github.io
+bug-reports:         https://github.com/Copilot-Language/copilot/issues
+stability:           Experimental
+category:            Language, Embedded
+build-type:          Simple
+extra-source-files:  README.md, CHANGELOG
+data-files:          data/tikz.latex
+                     data/timeline.html
+
+x-curation: uncurated
+
+source-repository head
+    type:       git
+    location:   https://github.com/Copilot-Language/copilot.git
+    subdir:     copilot-visualizer
+
+executable copilot-live-backend
+  default-language:  Haskell2010
+
+  main-is: Copilot/Live.hs
+
+  hs-source-dirs:    src
+
+  ghc-options:
+    -Wall
+
+  build-depends:
+    base       >= 4.9   && < 5,
+    aeson,
+    directory,
+    filepath,
+    hint,
+    pretty     >= 1.0   && < 1.2,
+    ogma-extra >= 1.6.0 && < 1.7,
+
+    copilot-core        >= 4.2 && < 4.3,
+    copilot-interpreter >= 4.2 && < 4.3,
+    copilot-visualizer  >= 4.2 && < 4.3,
+    copilot-language,
+    copilot,
+    text,
+    websockets >= 0.12.7
+
+  other-modules:
+
+    Paths_copilot_visualizer
+
+library
+
+  default-language:  Haskell2010
+
+  hs-source-dirs:    src
+
+  ghc-options:
+    -Wall
+
+  build-depends:
+    base       >= 4.9   && < 5,
+    aeson,
+    directory,
+    filepath,
+    pretty     >= 1.0   && < 1.2,
+    ogma-extra >= 1.6.0 && < 1.7,
+
+    copilot-core        >= 4.2 && < 4.3,
+    copilot-interpreter >= 4.2 && < 4.3
+
+  exposed-modules:
+
+    Copilot.Visualize
+
+  other-modules:
+
+    Paths_copilot_visualizer

copilot-visualizer.cabal

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+{{=<% %>=}}
+\documentclass{standalone}
+\usepackage{tikz}
+\usepackage{tikz-timing}
+\usepackage{xcolor}
+\definecolor{false}{HTML}{ECD9ED}
+\definecolor{true}{HTML}{D9ECED}
+\begin{document}
+\newcommand{\true}{T}
+\newcommand{\false}{F}
+\tikzset{
+every picture/.style={
+  execute at end picture={
+    \path (current bounding box.south west) +(-1,-1) (current bounding box.north east) +(1,1);
+    }
+}
+}
+
+\tikzset{
+timing/.style={x=5ex,y=2ex},
+timing/rowdist=4ex,
+timing/dslope=0.1,
+x=5ex,
+timing/coldist=1ex,
+timing/name/.style={font=\sffamily\scriptsize},
+timing/d/text/.style={font=\sffamily\tiny},
+}
+\begin{tikztimingtable}
+<%#adTraceElems%>
+<%teName%> & g<%#teValues%><%#tvIsEmpty%>S<%/tvIsEmpty%><%^tvIsEmpty%><%#teIsBoolean%>[fill=<%tvValue%>]D{\<%tvValue%>}<%/teIsBoolean%><%^teIsBoolean%>D{<%tvValue%>}<%/teIsBoolean%><%/tvIsEmpty%><%/teValues%>\\
+<%/adTraceElems%>
+\extracode
+\begin{background}[shift={(0.05,0)},help lines]
+\vertlines[help lines,opacity=0.3]{-0.3ex,...,<%adLastSample%>}
+\end{background}
+\end{tikztimingtable}
+\end{document}