1042 lines
37 KiB
HTML
1042 lines
37 KiB
HTML
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Python Preserves
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Preserves Path
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<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><!--! Font Awesome Free 6.4.2 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2023 Fonticons, Inc.--><path d="M439.55 236.05 244 40.45a28.87 28.87 0 0 0-40.81 0l-40.66 40.63 51.52 51.52c27.06-9.14 52.68 16.77 43.39 43.68l49.66 49.66c34.23-11.8 61.18 31 35.47 56.69-26.49 26.49-70.21-2.87-56-37.34L240.22 199v121.85c25.3 12.54 22.26 41.85 9.08 55a34.34 34.34 0 0 1-48.55 0c-17.57-17.6-11.07-46.91 11.25-56v-123c-20.8-8.51-24.6-30.74-18.64-45L142.57 101 8.45 235.14a28.86 28.86 0 0 0 0 40.81l195.61 195.6a28.86 28.86 0 0 0 40.8 0l194.69-194.69a28.86 28.86 0 0 0 0-40.81z"/></svg>
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GitLab
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<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M12 8a3 3 0 0 0 3-3 3 3 0 0 0-3-3 3 3 0 0 0-3 3 3 3 0 0 0 3 3m0 3.54C9.64 9.35 6.5 8 3 8v11c3.5 0 6.64 1.35 9 3.54 2.36-2.19 5.5-3.54 9-3.54V8c-3.5 0-6.64 1.35-9 3.54Z"/></svg>
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Python Preserves
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<a href="https://gitlab.com/preserves/preserves" title="Go to repository" class="md-source" data-md-component="source">
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<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 448 512"><!--! Font Awesome Free 6.4.2 by @fontawesome - https://fontawesome.com License - https://fontawesome.com/license/free (Icons: CC BY 4.0, Fonts: SIL OFL 1.1, Code: MIT License) Copyright 2023 Fonticons, Inc.--><path d="M439.55 236.05 244 40.45a28.87 28.87 0 0 0-40.81 0l-40.66 40.63 51.52 51.52c27.06-9.14 52.68 16.77 43.39 43.68l49.66 49.66c34.23-11.8 61.18 31 35.47 56.69-26.49 26.49-70.21-2.87-56-37.34L240.22 199v121.85c25.3 12.54 22.26 41.85 9.08 55a34.34 34.34 0 0 1-48.55 0c-17.57-17.6-11.07-46.91 11.25-56v-123c-20.8-8.51-24.6-30.74-18.64-45L142.57 101 8.45 235.14a28.86 28.86 0 0 0 0 40.81l195.61 195.6a28.86 28.86 0 0 0 40.8 0l194.69-194.69a28.86 28.86 0 0 0 0-40.81z"/></svg>
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GitLab
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</a>
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</div>
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<ul class="md-nav__list" data-md-scrollfix>
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<a href=".." class="md-nav__link">
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<span class="md-ellipsis">
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Overview
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</span>
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</a>
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</li>
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<li class="md-nav__item">
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<a href="../api/" class="md-nav__link">
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<span class="md-ellipsis">
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The top-level preserves package
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</span>
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</a>
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</li>
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<li class="md-nav__item">
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<a href="../binary/" class="md-nav__link">
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<span class="md-ellipsis">
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Machine-oriented binary syntax
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</span>
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</a>
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<li class="md-nav__item">
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<a href="../compare/" class="md-nav__link">
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<span class="md-ellipsis">
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Comparing Values
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</span>
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</a>
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<li class="md-nav__item">
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<a href="../error/" class="md-nav__link">
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<span class="md-ellipsis">
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Codec errors
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</span>
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</a>
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<li class="md-nav__item">
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<a href="../fold/" class="md-nav__link">
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<span class="md-ellipsis">
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Traversing values
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</span>
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</a>
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</li>
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<li class="md-nav__item">
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<a href="../merge/" class="md-nav__link">
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<span class="md-ellipsis">
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Merging values
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</span>
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</a>
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</li>
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<li class="md-nav__item md-nav__item--active">
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<input class="md-nav__toggle md-toggle" type="checkbox" id="__toc">
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<label class="md-nav__link md-nav__link--active" for="__toc">
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<span class="md-ellipsis">
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Preserves Path
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</span>
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<span class="md-nav__icon md-icon"></span>
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</label>
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<a href="./" class="md-nav__link md-nav__link--active">
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<span class="md-ellipsis">
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Preserves Path
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</span>
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</a>
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<nav class="md-nav md-nav--secondary" aria-label="Table of contents">
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<label class="md-nav__title" for="__toc">
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<span class="md-nav__icon md-icon"></span>
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Table of contents
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</label>
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<ul class="md-nav__list" data-md-component="toc" data-md-scrollfix>
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<li class="md-nav__item">
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<a href="#preserves.path" class="md-nav__link">
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path
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</a>
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<nav class="md-nav" aria-label="path">
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<ul class="md-nav__list">
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<li class="md-nav__item">
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<a href="#preserves.path--command-line-usage" class="md-nav__link">
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Command-line usage
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</a>
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</li>
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<li class="md-nav__item">
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<a href="#preserves.path--examples" class="md-nav__link">
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Examples
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</a>
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<nav class="md-nav" aria-label="Examples">
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<ul class="md-nav__list">
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<li class="md-nav__item">
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<a href="#preserves.path--setup-loading-test-data" class="md-nav__link">
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Setup: Loading test data
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</a>
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</li>
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<li class="md-nav__item">
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<a href="#preserves.path--example-1-selecting-string-valued-documentation-annotations" class="md-nav__link">
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Example 1: Selecting string-valued documentation annotations
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</a>
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</li>
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<li class="md-nav__item">
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<a href="#preserves.path--example-2-selecting-tests-with-records-as-their-annotatedvalues" class="md-nav__link">
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Example 2: Selecting tests with Records as their annotatedValues
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</a>
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</li>
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</ul>
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</nav>
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</li>
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</ul>
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</nav>
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</li>
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<li class="md-nav__item">
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<a href="#preserves.path.Predicate" class="md-nav__link">
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Predicate
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</a>
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</li>
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<li class="md-nav__item">
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<a href="#preserves.path.Selector" class="md-nav__link">
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Selector
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</a>
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</li>
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<li class="md-nav__item">
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<a href="#preserves.path.syntax" class="md-nav__link">
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syntax
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</a>
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</li>
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<li class="md-nav__item">
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<a href="#preserves.path.exec" class="md-nav__link">
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exec()
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</a>
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</li>
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<li class="md-nav__item">
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<a href="#preserves.path.parse" class="md-nav__link">
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parse()
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</a>
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</li>
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</ul>
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</nav>
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<li class="md-nav__item">
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<a href="../schema/" class="md-nav__link">
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<span class="md-ellipsis">
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Preserves Schema
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</span>
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</a>
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</li>
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<li class="md-nav__item">
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<a href="../text/" class="md-nav__link">
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<span class="md-ellipsis">
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Human-readable text syntax
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</span>
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</a>
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</li>
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<li class="md-nav__item">
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<a href="../values/" class="md-nav__link">
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<span class="md-ellipsis">
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Representations of Values
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</span>
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</a>
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</li>
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</ul>
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<span class="md-nav__icon md-icon"></span>
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Table of contents
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<ul class="md-nav__list" data-md-component="toc" data-md-scrollfix>
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<li class="md-nav__item">
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path
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<a href="#preserves.path--command-line-usage" class="md-nav__link">
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Command-line usage
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Examples
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<a href="#preserves.path--setup-loading-test-data" class="md-nav__link">
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Setup: Loading test data
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</a>
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</li>
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<li class="md-nav__item">
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<a href="#preserves.path--example-1-selecting-string-valued-documentation-annotations" class="md-nav__link">
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Example 1: Selecting string-valued documentation annotations
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</a>
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</li>
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<li class="md-nav__item">
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<a href="#preserves.path--example-2-selecting-tests-with-records-as-their-annotatedvalues" class="md-nav__link">
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Example 2: Selecting tests with Records as their annotatedValues
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</a>
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</ul>
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<a href="#preserves.path.Predicate" class="md-nav__link">
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Predicate
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</a>
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</li>
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<li class="md-nav__item">
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<a href="#preserves.path.Selector" class="md-nav__link">
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Selector
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</a>
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</li>
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<li class="md-nav__item">
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<a href="#preserves.path.syntax" class="md-nav__link">
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syntax
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<li class="md-nav__item">
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<a href="#preserves.path.exec" class="md-nav__link">
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exec()
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</a>
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</li>
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<li class="md-nav__item">
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<a href="#preserves.path.parse" class="md-nav__link">
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parse()
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</a>
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</li>
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</ul>
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</nav>
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<div class="md-content" data-md-component="content">
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<article class="md-content__inner md-typeset">
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<h1 id="preserves-path">Preserves Path</h1>
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<div class="doc doc-object doc-module">
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<a id="preserves.path"></a>
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<div class="doc doc-contents first">
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<p>The <a class="autorefs autorefs-internal" href="#preserves.path">preserves.path</a> module implements <a href="https://preserves.dev/preserves-path.html">Preserves
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Path</a>.</p>
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<p>Preserves Path is roughly analogous to
|
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<a href="https://www.w3.org/TR/2017/REC-xpath-31-20170321/">XPath</a>, but for Preserves values: just as
|
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XPath selects portions of an XML document, a Preserves Path uses <em>path expressions</em> to select
|
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portions of a <code>Value</code>.</p>
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<p>Use <a class="autorefs autorefs-internal" href="#preserves.path.parse">parse</a> to compile a path expression, and then use the
|
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<a class="autorefs autorefs-internal" href="#preserves.path.exec">exec</a> method on the result to apply it to a given input:</p>
|
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<div class="highlight"><pre><span></span><code><span class="n">parse</span><span class="p">(</span><span class="n">PATH_EXPRESSION_STRING</span><span class="p">)</span><span class="o">.</span><span class="n">exec</span><span class="p">(</span><span class="n">PRESERVES_VALUE</span><span class="p">)</span>
|
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<span class="o">-></span> <span class="n">SEQUENCE_OF_PRESERVES_VALUES</span>
|
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</code></pre></div>
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<h3 id="preserves.path--command-line-usage">Command-line usage</h3>
|
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<p>When <a class="autorefs autorefs-internal" href="#preserves.path">preserves.path</a> is run as a <code>__main__</code> module, <code>sys.argv[1]</code> is
|
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<a class="autorefs autorefs-internal" href="#preserves.path.parse">parsed</a>, interpreted as a path expression, and
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<a class="autorefs autorefs-internal" href="#preserves.path.exec">run</a> against <a class="autorefs autorefs-internal" href="../text/#preserves.text">human-readable values</a> read from standard
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input. Each matching result is passed to <a class="autorefs autorefs-internal" href="../text/#preserves.text.stringify">stringify</a> and printed to
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standard output.</p>
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<h3 id="preserves.path--examples">Examples</h3>
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<h4 id="preserves.path--setup-loading-test-data">Setup: Loading test data</h4>
|
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<p>The following examples use <code>testdata</code>:</p>
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<div class="highlight"><pre><span></span><code><span class="o">>>></span> <span class="k">with</span> <span class="nb">open</span><span class="p">(</span><span class="s1">'tests/samples.bin'</span><span class="p">,</span> <span class="s1">'rb'</span><span class="p">)</span> <span class="k">as</span> <span class="n">f</span><span class="p">:</span>
|
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<span class="o">...</span> <span class="n">testdata</span> <span class="o">=</span> <span class="n">decode_with_annotations</span><span class="p">(</span><span class="n">f</span><span class="o">.</span><span class="n">read</span><span class="p">())</span>
|
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</code></pre></div>
|
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<p>Recall that <code>samples.bin</code> contains a binary-syntax form of the human-readable
|
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[<code>samples.pr](https://preserves.dev/tests/samples.pr) test data file, intended to exercise most
|
|
of the features of Preserves. In particular, the root</code>Value` in the file has a number of
|
|
annotations (for documentation and other purposes).</p>
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<h4 id="preserves.path--example-1-selecting-string-valued-documentation-annotations">Example 1: Selecting string-valued documentation annotations</h4>
|
|
<p>The path expression <code>.annotations ^ Documentation . 0 / string</code> proceeds in five steps:</p>
|
|
<ol>
|
|
<li><code>.annotations</code> selects each annotation on the root document</li>
|
|
<li><code>^ Documentation</code> retains only those values (each an annotation of the root) that are <code>Record</code>s with label equal to the symbol <code>Documentation</code></li>
|
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<li><code>. 0</code> moves into the first child (the first field) of each such <code>Record</code>, which in our case is a list of other <code>Value</code>s</li>
|
|
<li><code>/</code> selects all immediate children of these lists</li>
|
|
<li><code>string</code> retains only those values that are strings</li>
|
|
</ol>
|
|
<p>The result of evaluating it on <code>testdata</code> is as follows:</p>
|
|
<div class="highlight"><pre><span></span><code><span class="o">>>></span> <span class="n">selector</span> <span class="o">=</span> <span class="n">parse</span><span class="p">(</span><span class="s1">'.annotations ^ Documentation . 0 / string'</span><span class="p">)</span>
|
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<span class="o">>>></span> <span class="k">for</span> <span class="n">result</span> <span class="ow">in</span> <span class="n">selector</span><span class="o">.</span><span class="n">exec</span><span class="p">(</span><span class="n">testdata</span><span class="p">):</span>
|
|
<span class="o">...</span> <span class="nb">print</span><span class="p">(</span><span class="n">stringify</span><span class="p">(</span><span class="n">result</span><span class="p">))</span>
|
|
<span class="s2">"Individual test cases may be any of the following record types:"</span>
|
|
<span class="s2">"In each test, let stripped = strip(annotatedValue),"</span>
|
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<span class="s2">" encodeBinary(·) produce canonical ordering and no annotations,"</span>
|
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<span class="s2">" looseEncodeBinary(·) produce any ordering, but with annotations,"</span>
|
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<span class="s2">" annotatedBinary(·) produce canonical ordering, but with annotations,"</span>
|
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<span class="s2">" decodeBinary(·) include annotations,"</span>
|
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<span class="s2">" encodeText(·) include annotations,"</span>
|
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<span class="s2">" decodeText(·) include annotations,"</span>
|
|
<span class="s2">"and check the following numbered expectations according to the table above:"</span>
|
|
<span class="s2">"Implementations may vary in their treatment of the difference between expectations"</span>
|
|
<span class="s2">"21/22 and 31/32, depending on how they wish to treat end-of-stream conditions."</span>
|
|
</code></pre></div>
|
|
<h4 id="preserves.path--example-2-selecting-tests-with-records-as-their-annotatedvalues">Example 2: Selecting tests with Records as their annotatedValues</h4>
|
|
<p>The path expression <code>// [.^ [= Test + = NondeterministicTest]] [. 1 rec]</code> proceeds in three steps:</p>
|
|
<ol>
|
|
<li>
|
|
<p><code>//</code> recursively decomposes the input, yielding all direct and indirect descendants of each input value</p>
|
|
</li>
|
|
<li>
|
|
<p><code>[.^ [= Test + = NondeterministicTest]]</code> retains only those inputs (each a descendant of the root) that yield more than zero results when executed against the expression within the brackets:</p>
|
|
<ol>
|
|
<li><code>.^</code> selects only labels of values that are <code>Records</code>, filtering by type and transforming in a single step</li>
|
|
<li><code>[= Test + = NondeterministicTest]</code> again filters by a path expression:<ol>
|
|
<li>the infix <code>+</code> operator takes the <em>union</em> of matches of its arguments</li>
|
|
<li>the left-hand argument, <code>= Test</code> selects values (remember, record labels) equal to the symbol <code>Test</code></li>
|
|
<li>the right-hand argument <code>= NondeterministicTest</code> selects values equal to <code>NondeterministicTest</code></li>
|
|
</ol>
|
|
</li>
|
|
</ol>
|
|
<p>The result is thus all <code>Record</code>s anywhere inside <code>testdata</code> that have either <code>Test</code> or <code>NondeterministicTest</code> as their labels.</p>
|
|
</li>
|
|
<li>
|
|
<p><code>[. 1 rec]</code> filters these <code>Record</code>s by another path expression:</p>
|
|
<ol>
|
|
<li><code>. 1</code> selects their second field (fields are numbered from 0)</li>
|
|
<li><code>rec</code> retains only values that are <code>Record</code>s</li>
|
|
</ol>
|
|
</li>
|
|
</ol>
|
|
<p>Evaluating the expression against <code>testdata</code> yields the following:</p>
|
|
<div class="highlight"><pre><span></span><code><span class="o">>>></span> <span class="n">selector</span> <span class="o">=</span> <span class="n">parse</span><span class="p">(</span><span class="s1">'// [.^ [= Test + = NondeterministicTest]] [. 1 rec]'</span><span class="p">)</span>
|
|
<span class="o">>>></span> <span class="k">for</span> <span class="n">result</span> <span class="ow">in</span> <span class="n">selector</span><span class="o">.</span><span class="n">exec</span><span class="p">(</span><span class="n">testdata</span><span class="p">):</span>
|
|
<span class="o">...</span> <span class="nb">print</span><span class="p">(</span><span class="n">stringify</span><span class="p">(</span><span class="n">result</span><span class="p">))</span>
|
|
<span class="o"><</span><span class="n">Test</span> <span class="c1">#[tLMHY2FwdHVyZbSzB2Rpc2NhcmSEhA==] <capture <discard>>></span>
|
|
<span class="o"><</span><span class="n">Test</span> <span class="c1">#[tLMHb2JzZXJ2ZbSzBXNwZWFrtLMHZGlzY2FyZIS0swdjYXB0dXJltLMHZGlzY2FyZISEhIQ=] <observe <speak <discard> <capture <discard>>>>></span>
|
|
<span class="o"><</span><span class="n">Test</span> <span class="c1">#[tLWzBnRpdGxlZLMGcGVyc29usAECswV0aGluZ7ABAYSwAWWxCUJsYWNrd2VsbLSzBGRhdGWwAgcdsAECsAEDhLECRHKE] <[titled person 2 thing 1] 101 "Blackwell" <date 1821 2 3> "Dr">></span>
|
|
<span class="o"><</span><span class="n">Test</span> <span class="c1">#[tLMHZGlzY2FyZIQ=] <discard>></span>
|
|
<span class="o"><</span><span class="n">Test</span> <span class="c1">#[tLABB7WEhA==] <7 []>></span>
|
|
<span class="o"><</span><span class="n">Test</span> <span class="c1">#[tLMHZGlzY2FyZLMIc3VycHJpc2WE] <discard surprise>></span>
|
|
<span class="o"><</span><span class="n">Test</span> <span class="c1">#[tLEHYVN0cmluZ7ABA7ABBIQ=] <"aString" 3 4>></span>
|
|
<span class="o"><</span><span class="n">Test</span> <span class="c1">#[tLSzB2Rpc2NhcmSEsAEDsAEEhA==] <<discard> 3 4>></span>
|
|
<span class="o"><</span><span class="n">Test</span> <span class="c1">#[hbMCYXK0swFShbMCYWazAWaE] @ar <R @af f>></span>
|
|
<span class="o"><</span><span class="n">Test</span> <span class="c1">#[tIWzAmFyswFShbMCYWazAWaE] <@ar R @af f>></span>
|
|
</code></pre></div>
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<div class="doc doc-children">
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<div class="doc doc-object doc-attribute">
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<h2 id="preserves.path.Predicate" class="doc doc-heading">
|
|
<code class="highlight language-python"><span class="n">Predicate</span> <span class="o">=</span> <span class="n">syntax</span><span class="o">.</span><span class="n">Predicate</span></code>
|
|
|
|
<span class="doc doc-labels">
|
|
<small class="doc doc-label doc-label-module-attribute"><code>module-attribute</code></small>
|
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</span>
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</h2>
|
|
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<div class="doc doc-contents ">
|
|
|
|
<p>Schema definition for representing a Preserves Path <code>Predicate</code>.</p>
|
|
</div>
|
|
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</div>
|
|
|
|
<div class="doc doc-object doc-attribute">
|
|
|
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|
|
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<h2 id="preserves.path.Selector" class="doc doc-heading">
|
|
<code class="highlight language-python"><span class="n">Selector</span> <span class="o">=</span> <span class="n">syntax</span><span class="o">.</span><span class="n">Selector</span></code>
|
|
|
|
<span class="doc doc-labels">
|
|
<small class="doc doc-label doc-label-module-attribute"><code>module-attribute</code></small>
|
|
</span>
|
|
|
|
</h2>
|
|
|
|
|
|
<div class="doc doc-contents ">
|
|
|
|
<p>Schema definition for representing a sequence of Preserves Path <code>Step</code>s.</p>
|
|
</div>
|
|
|
|
</div>
|
|
|
|
<div class="doc doc-object doc-attribute">
|
|
|
|
|
|
|
|
|
|
<h2 id="preserves.path.syntax" class="doc doc-heading">
|
|
<code class="highlight language-python"><span class="n">syntax</span> <span class="o">=</span> <span class="n">load_schema_file</span><span class="p">(</span><span class="n">pathlib</span><span class="o">.</span><span class="n">Path</span><span class="p">(</span><span class="vm">__file__</span><span class="p">)</span><span class="o">.</span><span class="n">parent</span> <span class="o">/</span> <span class="s1">'path.prb'</span><span class="p">)</span><span class="o">.</span><span class="n">path</span></code>
|
|
|
|
<span class="doc doc-labels">
|
|
<small class="doc doc-label doc-label-module-attribute"><code>module-attribute</code></small>
|
|
</span>
|
|
|
|
</h2>
|
|
|
|
|
|
<div class="doc doc-contents ">
|
|
|
|
<p>This value is a Python representation of a <a class="autorefs autorefs-internal" href="../schema/#preserves.schema">Preserves Schema</a> definition
|
|
for the Preserves Path expression language. The language is defined in the file
|
|
<a href="https://preserves.dev/path/path.prs">path.prs</a>.</p>
|
|
</div>
|
|
|
|
</div>
|
|
|
|
|
|
|
|
|
|
<div class="doc doc-object doc-function">
|
|
|
|
|
|
|
|
|
|
<h2 id="preserves.path.exec" class="doc doc-heading">
|
|
<code class="highlight language-python"><span class="n">exec</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">v</span><span class="p">)</span></code>
|
|
|
|
</h2>
|
|
|
|
|
|
<div class="doc doc-contents ">
|
|
|
|
<p>WARNING: This is not a <em>function</em>: it is a <em>method</em> on
|
|
<a class="autorefs autorefs-internal" href="#preserves.path.Selector">Selector</a>, <a class="autorefs autorefs-internal" href="#preserves.path.Predicate">Predicate</a>, and so on.</p>
|
|
<div class="highlight"><pre><span></span><code><span class="o">>>></span> <span class="n">sel</span> <span class="o">=</span> <span class="n">parse</span><span class="p">(</span><span class="s1">'/ [.length gt 1]'</span><span class="p">)</span>
|
|
<span class="o">>>></span> <span class="n">sel</span><span class="o">.</span><span class="n">exec</span><span class="p">([</span><span class="s1">''</span><span class="p">,</span> <span class="s1">'a'</span><span class="p">,</span> <span class="s1">'ab'</span><span class="p">,</span> <span class="s1">'abc'</span><span class="p">,</span> <span class="s1">'abcd'</span><span class="p">,</span> <span class="s1">'bcd'</span><span class="p">,</span> <span class="s1">'cd'</span><span class="p">,</span> <span class="s1">'d'</span><span class="p">,</span> <span class="s1">''</span><span class="p">])</span>
|
|
<span class="p">(</span><span class="s1">'ab'</span><span class="p">,</span> <span class="s1">'abc'</span><span class="p">,</span> <span class="s1">'abcd'</span><span class="p">,</span> <span class="s1">'bcd'</span><span class="p">,</span> <span class="s1">'cd'</span><span class="p">)</span>
|
|
</code></pre></div>
|
|
|
|
<details class="quote">
|
|
<summary>Source code in <code>preserves/path.py</code></summary>
|
|
<div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span></span><span class="normal">523</span>
|
|
<span class="normal">524</span>
|
|
<span class="normal">525</span>
|
|
<span class="normal">526</span>
|
|
<span class="normal">527</span>
|
|
<span class="normal">528</span>
|
|
<span class="normal">529</span>
|
|
<span class="normal">530</span>
|
|
<span class="normal">531</span>
|
|
<span class="normal">532</span>
|
|
<span class="normal">533</span>
|
|
<span class="normal">534</span>
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<span class="normal">535</span>
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<span class="normal">536</span></pre></div></td><td class="code"><div><pre><span></span><code><span class="nd">@extend</span><span class="p">(</span><span class="n">syntax</span><span class="o">.</span><span class="n">Function</span><span class="p">)</span>
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<span class="k">def</span> <span class="nf">exec</span><span class="p">(</span><span class="bp">self</span><span class="p">,</span> <span class="n">v</span><span class="p">):</span>
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<span class="w"> </span><span class="sd">"""WARNING: This is not a *function*: it is a *method* on</span>
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<span class="sd"> [Selector][preserves.path.Selector], [Predicate][preserves.path.Predicate], and so on.</span>
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<span class="sd"> ```python</span>
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<span class="sd"> >>> sel = parse('/ [.length gt 1]')</span>
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<span class="sd"> >>> sel.exec(['', 'a', 'ab', 'abc', 'abcd', 'bcd', 'cd', 'd', ''])</span>
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<span class="sd"> ('ab', 'abc', 'abcd', 'bcd', 'cd')</span>
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<span class="sd"> ```</span>
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<span class="sd"> """</span>
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<span class="k">return</span> <span class="p">(</span><span class="nb">len</span><span class="p">(</span><span class="bp">self</span><span class="o">.</span><span class="n">selector</span><span class="o">.</span><span class="n">exec</span><span class="p">(</span><span class="n">v</span><span class="p">)),)</span>
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</code></pre></div></td></tr></table></div>
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</details>
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</div>
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</div>
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<div class="doc doc-object doc-function">
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<h2 id="preserves.path.parse" class="doc doc-heading">
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<code class="highlight language-python"><span class="n">parse</span><span class="p">(</span><span class="n">s</span><span class="p">)</span></code>
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</h2>
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<div class="doc doc-contents ">
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<p>Parse <code>s</code> as a Preserves Path path expression, yielding a
|
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<a class="autorefs autorefs-internal" href="#preserves.path.Selector">Selector</a> object. Selectors (and Predicates etc.) have an
|
|
<a class="autorefs autorefs-internal" href="#preserves.path.exec">exec</a> method defined on them.</p>
|
|
<p>Raises <code>ValueError</code> if <code>s</code> is not a valid path expression.</p>
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<details class="quote">
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<summary>Source code in <code>preserves/path.py</code></summary>
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<div class="highlight"><table class="highlighttable"><tr><td class="linenos"><div class="linenodiv"><pre><span></span><span class="normal">131</span>
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<span class="normal">132</span>
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<span class="normal">133</span>
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<span class="normal">134</span>
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<span class="normal">135</span>
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<span class="normal">136</span>
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<span class="normal">137</span>
|
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<span class="normal">138</span>
|
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<span class="normal">139</span></pre></div></td><td class="code"><div><pre><span></span><code><span class="k">def</span> <span class="nf">parse</span><span class="p">(</span><span class="n">s</span><span class="p">):</span>
|
|
<span class="w"> </span><span class="sd">"""Parse `s` as a Preserves Path path expression, yielding a</span>
|
|
<span class="sd"> [Selector][preserves.path.Selector] object. Selectors (and Predicates etc.) have an</span>
|
|
<span class="sd"> [exec][preserves.path.exec] method defined on them.</span>
|
|
|
|
<span class="sd"> Raises `ValueError` if `s` is not a valid path expression.</span>
|
|
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|
<span class="sd"> """</span>
|
|
<span class="k">return</span> <span class="n">parse_selector</span><span class="p">(</span><span class="n">Parser</span><span class="p">(</span><span class="n">s</span><span class="p">))</span>
|
|
</code></pre></div></td></tr></table></div>
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</details>
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Last update:
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<span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date">March 16, 2023</span>
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<br>
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Created:
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<span class="git-revision-date-localized-plugin git-revision-date-localized-plugin-date">March 16, 2023</span>
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