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<li class="toctree-l1 current"><a class="current reference internal" href="#">Clauses key concepts</a><ul>
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<li class="toctree-l2"><a class="reference internal" href="#basic-clause-structure">Basic clause structure</a></li>
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<li class="toctree-l2"><a class="reference internal" href="#other-types-of-clauses">Other types of clauses</a><ul>
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<div class="section" id="clauses-key-concepts">
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<h1>Clauses key concepts<a class="headerlink" href="#clauses-key-concepts" title="Permalink to this headline">¶</a></h1>
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<div class="section" id="basic-clause-structure">
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<h2>Basic clause structure<a class="headerlink" href="#basic-clause-structure" title="Permalink to this headline">¶</a></h2>
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<p>A clause is a small building block for assembling contract verification logic, reusable and ready to test in separation.
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To see clauses in action go to: <a class="reference internal" href="tutorial-contract-clauses.html"><span class="doc">Writing a contract using clauses</span></a>.
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Let’s take a look at a simplified structure of the <code class="docutils literal"><span class="pre">Clause</span></code> class:</p>
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<div class="codeset container">
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<div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="k">abstract</span> <span class="k">class</span> <span class="nc">Clause</span><span class="p"><</span><span class="k">in</span> <span class="n">S</span> <span class="p">:</span> <span class="n">ContractState</span><span class="p">,</span> <span class="n">C</span> <span class="p">:</span> <span class="n">CommandData</span><span class="p">,</span> <span class="k">in</span> <span class="n">K</span> <span class="p">:</span> <span class="n">Any</span><span class="p">></span> <span class="p">{</span>
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<span class="cm">/** Determine whether this clause runs or not */</span>
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<span class="k">open</span> <span class="k">val</span> <span class="py">requiredCommands</span><span class="p">:</span> <span class="n">Set</span><span class="p"><</span><span class="n">Class</span><span class="p"><</span><span class="k">out</span> <span class="n">CommandData</span><span class="p">>></span> <span class="p">=</span> <span class="n">emptySet</span><span class="p">()</span>
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<span class="n">@Throws</span><span class="p">(</span><span class="n">IllegalStateException</span><span class="o">::</span><span class="k">class</span><span class="p">)</span>
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<span class="k">abstract</span> <span class="k">fun</span> <span class="nf">verify</span><span class="p">(</span><span class="n">tx</span><span class="p">:</span> <span class="n">TransactionForContract</span><span class="p">,</span>
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<span class="n">inputs</span><span class="p">:</span> <span class="n">List</span><span class="p"><</span><span class="n">S</span><span class="p">>,</span>
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<span class="n">outputs</span><span class="p">:</span> <span class="n">List</span><span class="p"><</span><span class="n">S</span><span class="p">>,</span>
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<span class="n">commands</span><span class="p">:</span> <span class="n">List</span><span class="p"><</span><span class="n">AuthenticatedObject</span><span class="p"><</span><span class="n">C</span><span class="p">>>,</span>
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<span class="n">groupingKey</span><span class="p">:</span> <span class="n">K</span><span class="p">?):</span> <span class="n">Set</span><span class="p"><</span><span class="n">C</span><span class="p">></span>
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<span class="p">...</span>
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<span class="p">}</span>
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</pre></div>
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</div>
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</div>
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<p>Basic clause structure contains two important components: <code class="docutils literal"><span class="pre">requiredCommands</span></code> and <code class="docutils literal"><span class="pre">verify</span></code> function.
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A clause is triggered when all <code class="docutils literal"><span class="pre">requiredCommands</span></code> are present in transaction’s command set (opposite inclusion doesn’t have to hold).
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Then the <code class="docutils literal"><span class="pre">verify</span></code> function is run, which checks if transaction meets conditions specified by this clause. Verification
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is no different than normal contract verification but using clauses it’s split into smaller generic code blocks with single verify method.</p>
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<p>When writing a contract you need to override the contract’s <code class="docutils literal"><span class="pre">verify</span></code> function which should call <code class="docutils literal"><span class="pre">verifyClause</span></code>. See: <a class="reference internal" href="tutorial-contract-clauses.html#verify-ref"><span class="std std-ref">Commercial paper class</span></a>.</p>
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<div class="admonition note">
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<p class="first admonition-title">Note</p>
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<p class="last">A clause <code class="docutils literal"><span class="pre">verify</span></code> function returns the set of processed commands, at the end of <code class="docutils literal"><span class="pre">verifyClause</span></code> execution
|
||
|
|
there is a check if all of transaction’s commands were matched. If not then an exception is raised. This is done to
|
||
|
|
enforce that spurious commands cannot be included in a transaction, ensuring that the transaction is as clear as
|
||
|
|
possible. As an example imagine a transaction with two commands: <code class="docutils literal"><span class="pre">Move</span></code> and <code class="docutils literal"><span class="pre">Issue</span></code> included, with verification written
|
||
|
|
using <code class="docutils literal"><span class="pre">FirstComposition</span></code> on clauses that require single command set. Thus only one of transaction’s commands will match
|
||
|
|
leaving the second unprocessed. It should raise an error - we want to ensure that commands set is minimal to simplify
|
||
|
|
analysis of intent of a transaction.</p>
|
||
|
|
</div>
|
||
|
|
<p>An example <code class="docutils literal"><span class="pre">verify</span></code> from <code class="docutils literal"><span class="pre">Obligation</span></code> contract:</p>
|
||
|
|
<div class="codeset container">
|
||
|
|
<div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="k">override</span> <span class="k">fun</span> <span class="nf">verify</span><span class="p">(</span><span class="n">tx</span><span class="p">:</span> <span class="n">TransactionForContract</span><span class="p">)</span> <span class="p">=</span> <span class="n">verifyClause</span><span class="p"><</span><span class="n">Commands</span><span class="p">>(</span><span class="n">tx</span><span class="p">,</span> <span class="n">FirstComposition</span><span class="p"><</span><span class="n">ContractState</span><span class="p">,</span> <span class="n">Commands</span><span class="p">,</span> <span class="n">Unit</span><span class="p">>(</span>
|
||
|
|
<span class="n">Clauses</span><span class="p">.</span><span class="n">Net</span><span class="p"><</span><span class="n">Commands</span><span class="p">,</span> <span class="n">P</span><span class="p">>(),</span>
|
||
|
|
<span class="n">Clauses</span><span class="p">.</span><span class="n">Group</span><span class="p"><</span><span class="n">P</span><span class="p">>()</span>
|
||
|
|
<span class="p">),</span> <span class="n">tx</span><span class="p">.</span><span class="n">commands</span><span class="p">.</span><span class="n">select</span><span class="p"><</span><span class="n">Obligation</span><span class="p">.</span><span class="n">Commands</span><span class="p">>())</span>
|
||
|
|
</pre></div>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<p>It takes transaction to be verified, and passes it along with a top-level clause and commands to the <code class="docutils literal"><span class="pre">verifyClause</span></code>
|
||
|
|
function. As you can see above we have used <code class="docutils literal"><span class="pre">FirstComposition</span></code> which is a special type of clause, which extends the
|
||
|
|
<code class="docutils literal"><span class="pre">CompositeClause</span></code> abstract class (in that particular case, it ensures that either <code class="docutils literal"><span class="pre">Net</span></code> or <code class="docutils literal"><span class="pre">Group</span></code> will run - for explanation see <a class="reference internal" href="#firstcomposition">FirstComposition</a>).
|
||
|
|
It’s a type of clause that adds support for encapsulating multiple clauses and defines common behaviour for that composition.
|
||
|
|
There is also a <code class="docutils literal"><span class="pre">GroupClauseVerifier</span></code> special clause, which specifies how to group transaction input/output states
|
||
|
|
together and passes them to adequate clause for further processing.</p>
|
||
|
|
</div>
|
||
|
|
<div class="section" id="composition-clauses">
|
||
|
|
<h2>Composition clauses<a class="headerlink" href="#composition-clauses" title="Permalink to this headline">¶</a></h2>
|
||
|
|
<p>One of the most important concepts of clauses - composition clauses which extend <code class="docutils literal"><span class="pre">CompositeClause</span></code> abstract class,
|
||
|
|
providing a range of ways of assembling clauses together. They define a logic of verification execution specifying which clauses
|
||
|
|
will be run.</p>
|
||
|
|
<div class="section" id="allcomposition">
|
||
|
|
<h3>AllComposition<a class="headerlink" href="#allcomposition" title="Permalink to this headline">¶</a></h3>
|
||
|
|
<p><strong>Description</strong></p>
|
||
|
|
<p>Composes a number of clauses, such that all of the clauses must run for verification to pass.</p>
|
||
|
|
<img alt="_images/allCompositionChart.png" src="_images/allCompositionChart.png" />
|
||
|
|
<p>Short description:</p>
|
||
|
|
<ul class="simple">
|
||
|
|
<li><code class="docutils literal"><span class="pre">AllComposition</span></code> holds clauses <em>Cl1,..,Cl5</em>.</li>
|
||
|
|
<li>Check if all clauses that compose <code class="docutils literal"><span class="pre">AllComposition</span></code> have associated commands in a command set - if not, verification fails.</li>
|
||
|
|
<li>After successful check runs verification logic specific for every clause <em>Cl1,..,Cl5</em> from that composition.</li>
|
||
|
|
</ul>
|
||
|
|
<p><strong>Usage</strong></p>
|
||
|
|
<p>See code in <a class="reference internal" href="#groupclauseverifier">GroupClauseVerifier</a>.</p>
|
||
|
|
</div>
|
||
|
|
<div class="section" id="anycomposition">
|
||
|
|
<h3>AnyComposition<a class="headerlink" href="#anycomposition" title="Permalink to this headline">¶</a></h3>
|
||
|
|
<p><strong>Description</strong></p>
|
||
|
|
<p>Composes a number of clauses, such that 0 or more of the clauses can be run.</p>
|
||
|
|
<img alt="_images/anyCompositionChart.png" src="_images/anyCompositionChart.png" />
|
||
|
|
<p>Short description:</p>
|
||
|
|
<ul class="simple">
|
||
|
|
<li>Checks if zero or more clauses that compose AnyComposition have associated commands in a command set.</li>
|
||
|
|
<li>After success runs verification logic specific for every <em>matched</em> (in this case <em>Cl2, Cl4, Cl5</em>) clause from composition.</li>
|
||
|
|
</ul>
|
||
|
|
<p><strong>Usage</strong></p>
|
||
|
|
<p>Example from <code class="docutils literal"><span class="pre">CommercialPaper.kt</span></code>:</p>
|
||
|
|
<div class="codeset container">
|
||
|
|
<div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">Group</span> <span class="p">:</span> <span class="n">GroupClauseVerifier</span><span class="p"><</span><span class="n">State</span><span class="p">,</span> <span class="n">Commands</span><span class="p">,</span> <span class="n">Issued</span><span class="p"><</span><span class="n">Terms</span><span class="p">>>(</span>
|
||
|
|
<span class="n">AnyComposition</span><span class="p">(</span>
|
||
|
|
<span class="n">Redeem</span><span class="p">(),</span>
|
||
|
|
<span class="n">Move</span><span class="p">(),</span>
|
||
|
|
<span class="n">Issue</span><span class="p">()))</span> <span class="p">{</span>
|
||
|
|
<span class="k">override</span> <span class="k">fun</span> <span class="nf">groupStates</span><span class="p">(</span><span class="n">tx</span><span class="p">:</span> <span class="n">TransactionForContract</span><span class="p">):</span> <span class="n">List</span><span class="p"><</span><span class="n">TransactionForContract</span><span class="p">.</span><span class="n">InOutGroup</span><span class="p"><</span><span class="n">State</span><span class="p">,</span> <span class="n">Issued</span><span class="p"><</span><span class="n">Terms</span><span class="p">>>></span>
|
||
|
|
<span class="p">=</span> <span class="n">tx</span><span class="p">.</span><span class="n">groupStates</span><span class="p"><</span><span class="n">State</span><span class="p">,</span> <span class="n">Issued</span><span class="p"><</span><span class="n">Terms</span><span class="p">>></span> <span class="p">{</span> <span class="n">it</span><span class="p">.</span><span class="n">token</span> <span class="p">}</span>
|
||
|
|
<span class="p">}</span>
|
||
|
|
</pre></div>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<div class="section" id="firstcomposition">
|
||
|
|
<h3>FirstComposition<a class="headerlink" href="#firstcomposition" title="Permalink to this headline">¶</a></h3>
|
||
|
|
<p><strong>Description</strong></p>
|
||
|
|
<p>Composes a number of clauses, such that the first match is run, and it errors if none is run.</p>
|
||
|
|
<img alt="_images/firstCompositionChart.png" src="_images/firstCompositionChart.png" />
|
||
|
|
<p>Short description:</p>
|
||
|
|
<ul class="simple">
|
||
|
|
<li>Takes first clause that matches and if none found throws an exception.</li>
|
||
|
|
<li>If successful runs verification on the clause that matched (in this case <em>Cl4</em>).</li>
|
||
|
|
</ul>
|
||
|
|
<p><strong>Usage</strong></p>
|
||
|
|
<p>See code in <a class="reference internal" href="#groupclauseverifier">GroupClauseVerifier</a>.</p>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<div class="section" id="other-types-of-clauses">
|
||
|
|
<h2>Other types of clauses<a class="headerlink" href="#other-types-of-clauses" title="Permalink to this headline">¶</a></h2>
|
||
|
|
<p>There are certain types of clauses that are specialized in particular types of contracts (like <code class="docutils literal"><span class="pre">AbstractIssue</span></code>) or generally
|
||
|
|
should be used as helpers in building parts of logic (the most important one is <code class="docutils literal"><span class="pre">GroupClauseVerifier</span></code>).</p>
|
||
|
|
<div class="section" id="groupclauseverifier">
|
||
|
|
<h3>GroupClauseVerifier<a class="headerlink" href="#groupclauseverifier" title="Permalink to this headline">¶</a></h3>
|
||
|
|
<p><strong>Description</strong></p>
|
||
|
|
<p>Groups input and output states according to <code class="docutils literal"><span class="pre">groupStates</span></code> function. Runs the top-level clause verification on each
|
||
|
|
group in turn.</p>
|
||
|
|
<img alt="_images/groupClauseVerifyChart.png" src="_images/groupClauseVerifyChart.png" />
|
||
|
|
<p>Short description:</p>
|
||
|
|
<p><code class="docutils literal"><span class="pre">GroupClauseVerifier</span></code> wraps clause <em>Cl1</em>. After grouping relevant states together with <code class="docutils literal"><span class="pre">groupStates</span></code> into three groups
|
||
|
|
<em>Gr1, Gr2, Gr3</em> runs <em>Cl1.verify(Gr1), Cl1.verify(Gr2), Cl1.verify(Gr3)</em>.</p>
|
||
|
|
<p>For more detailed example head to <a class="reference internal" href="tutorial-contract.html#state-ref"><span class="std std-ref">Using state groups</span></a>.</p>
|
||
|
|
<p><strong>Usage</strong></p>
|
||
|
|
<p>You need to extend <code class="docutils literal"><span class="pre">GroupClauseVerifier</span></code> clause and define <code class="docutils literal"><span class="pre">groupStates</span></code> function which takes transaction and returns
|
||
|
|
grouped input and output states with a grouping key used for each group. Example from <code class="docutils literal"><span class="pre">Obligation.kt</span></code> contract:</p>
|
||
|
|
<div class="codeset container">
|
||
|
|
<div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">Group</span><span class="p"><</span><span class="n">P</span><span class="p">></span> <span class="p">:</span> <span class="n">GroupClauseVerifier</span><span class="p"><</span><span class="n">State</span><span class="p"><</span><span class="n">P</span><span class="p">>,</span> <span class="n">Commands</span><span class="p">,</span> <span class="n">Issued</span><span class="p"><</span><span class="n">Terms</span><span class="p"><</span><span class="n">P</span><span class="p">>>>(</span>
|
||
|
|
<span class="n">AllComposition</span><span class="p">(</span>
|
||
|
|
<span class="n">NoZeroSizedOutputs</span><span class="p"><</span><span class="n">State</span><span class="p"><</span><span class="n">P</span><span class="p">>,</span> <span class="n">Commands</span><span class="p">,</span> <span class="n">Terms</span><span class="p"><</span><span class="n">P</span><span class="p">>>(),</span>
|
||
|
|
<span class="n">FirstComposition</span><span class="p">(</span>
|
||
|
|
<span class="n">SetLifecycle</span><span class="p"><</span><span class="n">P</span><span class="p">>(),</span>
|
||
|
|
<span class="n">AllComposition</span><span class="p">(</span>
|
||
|
|
<span class="n">VerifyLifecycle</span><span class="p"><</span><span class="n">State</span><span class="p"><</span><span class="n">P</span><span class="p">>,</span> <span class="n">Commands</span><span class="p">,</span> <span class="n">Issued</span><span class="p"><</span><span class="n">Terms</span><span class="p"><</span><span class="n">P</span><span class="p">>>,</span> <span class="n">P</span><span class="p">>(),</span>
|
||
|
|
<span class="n">FirstComposition</span><span class="p">(</span>
|
||
|
|
<span class="n">Settle</span><span class="p"><</span><span class="n">P</span><span class="p">>(),</span>
|
||
|
|
<span class="n">Issue</span><span class="p">(),</span>
|
||
|
|
<span class="n">ConserveAmount</span><span class="p">()</span>
|
||
|
|
<span class="p">)</span>
|
||
|
|
<span class="p">)</span>
|
||
|
|
<span class="p">)</span>
|
||
|
|
<span class="p">)</span>
|
||
|
|
<span class="p">)</span> <span class="p">{</span>
|
||
|
|
<span class="k">override</span> <span class="k">fun</span> <span class="nf">groupStates</span><span class="p">(</span><span class="n">tx</span><span class="p">:</span> <span class="n">TransactionForContract</span><span class="p">):</span> <span class="n">List</span><span class="p"><</span><span class="n">TransactionForContract</span><span class="p">.</span><span class="n">InOutGroup</span><span class="p"><</span><span class="n">Obligation</span><span class="p">.</span><span class="n">State</span><span class="p"><</span><span class="n">P</span><span class="p">>,</span> <span class="n">Issued</span><span class="p"><</span><span class="n">Terms</span><span class="p"><</span><span class="n">P</span><span class="p">>>>></span>
|
||
|
|
<span class="p">=</span> <span class="n">tx</span><span class="p">.</span><span class="n">groupStates</span><span class="p"><</span><span class="n">Obligation</span><span class="p">.</span><span class="n">State</span><span class="p"><</span><span class="n">P</span><span class="p">>,</span> <span class="n">Issued</span><span class="p"><</span><span class="n">Terms</span><span class="p"><</span><span class="n">P</span><span class="p">>>></span> <span class="p">{</span> <span class="n">it</span><span class="p">.</span><span class="n">amount</span><span class="p">.</span><span class="n">token</span> <span class="p">}</span>
|
||
|
|
<span class="p">}</span>
|
||
|
|
</pre></div>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<p>Usually it’s convenient to use <code class="docutils literal"><span class="pre">groupStates</span></code> function defined on <code class="docutils literal"><span class="pre">TransactionForContract</span></code> class. Which given a type and a
|
||
|
|
selector function, that returns a grouping key, associates inputs and outputs together so that they can be processed as one.
|
||
|
|
The grouping key is any arbitrary object that can act as a map key (so must implement equals and hashCode).</p>
|
||
|
|
</div>
|
||
|
|
<div class="section" id="abstractconserveamount">
|
||
|
|
<h3>AbstractConserveAmount<a class="headerlink" href="#abstractconserveamount" title="Permalink to this headline">¶</a></h3>
|
||
|
|
<p><strong>Description</strong></p>
|
||
|
|
<p>Standardised clause for checking input/output balances of fungible assets. Requires that a
|
||
|
|
Move command is provided, and errors if absent. Conserve amount clause can only be used on grouped states.</p>
|
||
|
|
<p><strong>Usage</strong></p>
|
||
|
|
<div class="codeset container">
|
||
|
|
<div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="cm">/**</span>
|
||
|
|
<span class="cm"> * Generic move/exit clause for fungible assets</span>
|
||
|
|
<span class="cm"> */</span>
|
||
|
|
<span class="k">class</span> <span class="nc">ConserveAmount</span><span class="p"><</span><span class="n">P</span><span class="p">></span> <span class="p">:</span> <span class="n">AbstractConserveAmount</span><span class="p"><</span><span class="n">State</span><span class="p"><</span><span class="n">P</span><span class="p">>,</span> <span class="n">Commands</span><span class="p">,</span> <span class="n">Terms</span><span class="p"><</span><span class="n">P</span><span class="p">>>()</span>
|
||
|
|
</pre></div>
|
||
|
|
</div>
|
||
|
|
</div>
|
||
|
|
<p>See code in <a class="reference internal" href="#groupclauseverifier">GroupClauseVerifier</a>.</p>
|
||
|
|
</div>
|
||
|
|
<div class="section" id="abstractissue">
|
||
|
|
<h3>AbstractIssue<a class="headerlink" href="#abstractissue" title="Permalink to this headline">¶</a></h3>
|
||
|
|
<p><strong>Description</strong></p>
|
||
|
|
<p>Standard issue clause for contracts that issue fungible assets.</p>
|
||
|
|
<p><strong>Usage</strong></p>
|
||
|
|
<p>Example from <code class="docutils literal"><span class="pre">CommercialPaper.kt</span></code>:</p>
|
||
|
|
<div class="codeset container">
|
||
|
|
<div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">Issue</span> <span class="p">:</span> <span class="n">AbstractIssue</span><span class="p"><</span><span class="n">State</span><span class="p">,</span> <span class="n">Commands</span><span class="p">,</span> <span class="n">Terms</span><span class="p">>(</span>
|
||
|
|
<span class="p">{</span> <span class="n">map</span> <span class="p">{</span> <span class="n">Amount</span><span class="p">(</span><span class="n">it</span><span class="p">.</span><span class="n">faceValue</span><span class="p">.</span><span class="n">quantity</span><span class="p">,</span> <span class="n">it</span><span class="p">.</span><span class="n">token</span><span class="p">)</span> <span class="p">}.</span><span class="n">sumOrThrow</span><span class="p">()</span> <span class="p">},</span>
|
||
|
|
<span class="p">{</span> <span class="n">token</span> <span class="p">-></span> <span class="n">map</span> <span class="p">{</span> <span class="n">Amount</span><span class="p">(</span><span class="n">it</span><span class="p">.</span><span class="n">faceValue</span><span class="p">.</span><span class="n">quantity</span><span class="p">,</span> <span class="n">it</span><span class="p">.</span><span class="n">token</span><span class="p">)</span> <span class="p">}.</span><span class="n">sumOrZero</span><span class="p">(</span><span class="n">token</span><span class="p">)</span> <span class="p">})</span> <span class="p">{</span>
|
||
|
|
<span class="k">override</span> <span class="k">val</span> <span class="py">requiredCommands</span><span class="p">:</span> <span class="n">Set</span><span class="p"><</span><span class="n">Class</span><span class="p"><</span><span class="k">out</span> <span class="n">CommandData</span><span class="p">>></span> <span class="p">=</span> <span class="n">setOf</span><span class="p">(</span><span class="n">Commands</span><span class="p">.</span><span class="n">Issue</span><span class="o">::</span><span class="k">class</span><span class="p">.</span><span class="n">java</span><span class="p">)</span>
|
||
|
|
|
||
|
|
<span class="k">override</span> <span class="k">fun</span> <span class="nf">verify</span><span class="p">(</span><span class="n">tx</span><span class="p">:</span> <span class="n">TransactionForContract</span><span class="p">,</span>
|
||
|
|
<span class="n">inputs</span><span class="p">:</span> <span class="n">List</span><span class="p"><</span><span class="n">State</span><span class="p">>,</span>
|
||
|
|
<span class="n">outputs</span><span class="p">:</span> <span class="n">List</span><span class="p"><</span><span class="n">State</span><span class="p">>,</span>
|
||
|
|
<span class="n">commands</span><span class="p">:</span> <span class="n">List</span><span class="p"><</span><span class="n">AuthenticatedObject</span><span class="p"><</span><span class="n">Commands</span><span class="p">>>,</span>
|
||
|
|
<span class="n">groupingKey</span><span class="p">:</span> <span class="n">Issued</span><span class="p"><</span><span class="n">Terms</span><span class="p">>?):</span> <span class="n">Set</span><span class="p"><</span><span class="n">Commands</span><span class="p">></span> <span class="p">{</span>
|
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<span class="k">val</span> <span class="py">consumedCommands</span> <span class="p">=</span> <span class="k">super</span><span class="p">.</span><span class="n">verify</span><span class="p">(</span><span class="n">tx</span><span class="p">,</span> <span class="n">inputs</span><span class="p">,</span> <span class="n">outputs</span><span class="p">,</span> <span class="n">commands</span><span class="p">,</span> <span class="n">groupingKey</span><span class="p">)</span>
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<span class="p">...</span>
|
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</pre></div>
|
||
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</div>
|
||
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</div>
|
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<p>First function in constructor converts a list of states into an amount of the token. Must error if there are no states in the list.
|
||
|
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Second function converts a list of states into an amount of the token, and returns zero if there are no states in the list.
|
||
|
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Takes in an instance of the token definition for constructing the zero amount if needed.</p>
|
||
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</div>
|
||
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<div class="section" id="nozerosizedoutputs">
|
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<h3>NoZeroSizedOutputs<a class="headerlink" href="#nozerosizedoutputs" title="Permalink to this headline">¶</a></h3>
|
||
|
|
<p><strong>Description</strong></p>
|
||
|
|
<p>Clause for fungible asset contracts, which enforces that no output state should have a balance of zero.</p>
|
||
|
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<p><strong>Usage</strong></p>
|
||
|
|
<p>See code in <a class="reference internal" href="#groupclauseverifier">GroupClauseVerifier</a>.</p>
|
||
|
|
</div>
|
||
|
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<div class="section" id="filteron">
|
||
|
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<h3>FilterOn<a class="headerlink" href="#filteron" title="Permalink to this headline">¶</a></h3>
|
||
|
|
<p><strong>Description</strong></p>
|
||
|
|
<p>Filter the states that are passed through to the wrapped clause, to restrict them to a specific type.</p>
|
||
|
|
<p><code class="docutils literal"><span class="pre">FilterOn</span></code> narrows the scope of the states being verified.
|
||
|
|
Let’s take a transaction with multiple cash states of different currencies, we want to run a clause that focuses
|
||
|
|
on only GBP cash states rather than all cash states.</p>
|
||
|
|
<p><strong>Usage</strong></p>
|
||
|
|
<div class="codeset container">
|
||
|
|
<div class="highlight-kotlin"><div class="highlight"><pre><span></span><span class="n">FilterOn</span><span class="p">(</span><span class="n">clause</span><span class="p">,</span> <span class="p">{</span> <span class="n">states</span> <span class="p">-></span> <span class="n">states</span><span class="p">.</span><span class="n">filter</span> <span class="p">{</span> <span class="n">it</span><span class="p">.</span><span class="n">amount</span><span class="p">.</span><span class="n">token</span> <span class="p">==</span> <span class="n">GBP</span><span class="p">}</span> <span class="p">})</span>
|
||
|
|
</pre></div>
|
||
|
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</div>
|
||
|
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</div>
|
||
|
|
<p>Takes <code class="docutils literal"><span class="pre">filterStates</span></code> function that limits states passed to <code class="docutils literal"><span class="pre">clause</span></code> verification.</p>
|
||
|
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|
||
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