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...hy-go-codegen/src/main/java/software/amazon/smithy/go/codegen/integration/Paginators.java
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/* | ||
* Copyright 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved. | ||
* | ||
* Licensed under the Apache License, Version 2.0 (the "License"). | ||
* You may not use this file except in compliance with the License. | ||
* A copy of the License is located at | ||
* | ||
* http://aws.amazon.com/apache2.0 | ||
* | ||
* or in the "license" file accompanying this file. This file is distributed | ||
* on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either | ||
* express or implied. See the License for the specific language governing | ||
* permissions and limitations under the License. | ||
*/ | ||
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package software.amazon.smithy.go.codegen.integration; | ||
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import java.util.List; | ||
import java.util.Optional; | ||
import java.util.function.Consumer; | ||
import java.util.stream.Collectors; | ||
import software.amazon.smithy.codegen.core.Symbol; | ||
import software.amazon.smithy.codegen.core.SymbolProvider; | ||
import software.amazon.smithy.go.codegen.GoSettings; | ||
import software.amazon.smithy.go.codegen.GoWriter; | ||
import software.amazon.smithy.go.codegen.SmithyGoDependency; | ||
import software.amazon.smithy.go.codegen.SymbolUtils; | ||
import software.amazon.smithy.go.codegen.TriConsumer; | ||
import software.amazon.smithy.model.Model; | ||
import software.amazon.smithy.model.knowledge.PaginatedIndex; | ||
import software.amazon.smithy.model.knowledge.PaginationInfo; | ||
import software.amazon.smithy.model.knowledge.TopDownIndex; | ||
import software.amazon.smithy.model.shapes.MemberShape; | ||
import software.amazon.smithy.model.shapes.ServiceShape; | ||
import software.amazon.smithy.model.traits.DocumentationTrait; | ||
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/** | ||
* Implements support for PaginatedTrait. | ||
*/ | ||
public class Paginators implements GoIntegration { | ||
@Override | ||
public void writeAdditionalFiles( | ||
GoSettings settings, | ||
Model model, | ||
SymbolProvider symbolProvider, | ||
TriConsumer<String, String, Consumer<GoWriter>> writerFactory | ||
) { | ||
ServiceShape serviceShape = settings.getService(model); | ||
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PaginatedIndex paginatedIndex = PaginatedIndex.of(model); | ||
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TopDownIndex topDownIndex = TopDownIndex.of(model); | ||
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List<PaginationInfo> paginationInfos = topDownIndex.getContainedOperations(serviceShape).stream() | ||
.map(operationShape -> paginatedIndex.getPaginationInfo(serviceShape, operationShape)) | ||
.filter(Optional::isPresent) | ||
.map(paginationInfo -> paginationInfo.get()) | ||
.collect(Collectors.toList()); | ||
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if (paginationInfos.size() == 0) { | ||
return; | ||
} | ||
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writerFactory.accept("paginators.go", settings.getModuleName(), writer -> { | ||
paginationInfos.forEach((paginationInfo) -> { | ||
generateOperationPaginator(model, symbolProvider, writer, paginationInfo); | ||
}); | ||
}); | ||
} | ||
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private void generateOperationPaginator( | ||
Model model, | ||
SymbolProvider symbolProvider, | ||
GoWriter writer, | ||
PaginationInfo paginationInfo | ||
) { | ||
Symbol operationSymbol = symbolProvider.toSymbol(paginationInfo.getOperation()); | ||
Symbol inputSymbol = symbolProvider.toSymbol(paginationInfo.getInput()); | ||
Symbol outputSymbol = symbolProvider.toSymbol(paginationInfo.getOutput()); | ||
Optional<MemberShape> pageSizeMember = paginationInfo.getPageSizeMember(); | ||
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Symbol interfaceSymbol = SymbolUtils.createValueSymbolBuilder(String.format("%sAPIClient", | ||
operationSymbol.getName())).build(); | ||
Symbol paginatorSymbol = SymbolUtils.createPointableSymbolBuilder(String.format("%sPaginator", | ||
operationSymbol.getName())).build(); | ||
Symbol optionsSymbol = SymbolUtils.createPointableSymbolBuilder(String.format("%sOptions", | ||
paginatorSymbol.getName())).build(); | ||
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writeClientOperationInterface(writer, operationSymbol, inputSymbol, outputSymbol, interfaceSymbol); | ||
writePaginatorOptions(model, symbolProvider, writer, operationSymbol, pageSizeMember, optionsSymbol); | ||
writePaginator(symbolProvider, writer, paginationInfo, operationSymbol, inputSymbol, outputSymbol, | ||
pageSizeMember, interfaceSymbol, paginatorSymbol, optionsSymbol); | ||
} | ||
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private void writePaginator( | ||
SymbolProvider symbolProvider, | ||
GoWriter writer, | ||
PaginationInfo paginationInfo, | ||
Symbol operationSymbol, | ||
Symbol inputSymbol, | ||
Symbol outputSymbol, | ||
Optional<MemberShape> pageSizeMember, | ||
Symbol interfaceSymbol, | ||
Symbol paginatorSymbol, | ||
Symbol optionsSymbol | ||
) { | ||
String inputMember = symbolProvider.toMemberName(paginationInfo.getInputTokenMember()); | ||
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writer.writeDocs(String.format("%s is a paginator for %s", paginatorSymbol, operationSymbol)); | ||
writer.openBlock("type $T struct {", "}", paginatorSymbol, () -> { | ||
writer.write("options $T", optionsSymbol); | ||
writer.write("client $T", interfaceSymbol); | ||
writer.write("params $P", inputSymbol); | ||
writer.write("nextToken *string"); | ||
writer.write("firstPage bool"); | ||
writer.write("done bool"); | ||
}); | ||
writer.write(""); | ||
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Symbol newPagiantor = SymbolUtils.createValueSymbolBuilder(String.format("New%s", | ||
paginatorSymbol.getName())).build(); | ||
writer.writeDocs(String.format("%s returns a new %s", newPagiantor.getName(), paginatorSymbol.getName())); | ||
writer.openBlock("func $T(client $T, params $P, optFns ...func($P)) $P {", "}", | ||
newPagiantor, interfaceSymbol, inputSymbol, optionsSymbol, paginatorSymbol, () -> { | ||
writer.write("options := $T{}", optionsSymbol); | ||
writer.openBlock("for _, fn := range optFns {", "}", () -> { | ||
writer.write("fn(&options)"); | ||
}); | ||
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writer.openBlock("return &$T{", "}", paginatorSymbol, () -> { | ||
writer.write("options: options,"); | ||
writer.write("client: client,"); | ||
writer.write("params: params,"); | ||
writer.write("firstPage: true,"); | ||
}); | ||
}); | ||
writer.write(""); | ||
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writer.writeDocs("HasMorePages returns a boolean indicating whether more pages are available"); | ||
writer.openBlock("func (p $P) HasMorePages() bool {", "}", paginatorSymbol, () -> { | ||
writer.openBlock("if p.done {", "}", () -> writer.write("return false")); | ||
writer.write("return p.firstPage || (p.nextToken != nil && len(*p.nextToken) > 0)"); | ||
}); | ||
writer.write(""); | ||
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Symbol contextSymbol = SymbolUtils.createValueSymbolBuilder("Context", SmithyGoDependency.CONTEXT) | ||
.build(); | ||
writer.writeDocs(String.format("NextPage retrieves the next %s page.", operationSymbol.getName())); | ||
writer.openBlock("func (p $P) NextPage(ctx $T, optFns ...func(*Options)) ($P, error) {", "}", | ||
paginatorSymbol, contextSymbol, outputSymbol, () -> { | ||
writer.addUseImports(SmithyGoDependency.FMT); | ||
writer.openBlock("if !p.HasMorePages() {", "}", () -> { | ||
writer.write("return nil, fmt.Errorf(\"no more pages available\")"); | ||
}); | ||
writer.write(""); | ||
writer.write("params := *p.params"); | ||
writer.write("params.$L = p.nextToken", inputMember); | ||
pageSizeMember.ifPresent(memberShape -> writer.write("params.$L = p.options.Limit", | ||
symbolProvider.toMemberName(memberShape))); | ||
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writer.write("result, err := p.client.$L(ctx, ¶ms, optFns...)", | ||
operationSymbol.getName()); | ||
writer.openBlock("if err != nil {", "}", () -> { | ||
writer.write("return nil, err"); | ||
}); | ||
writer.write("p.firstPage = false"); | ||
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StringBuilder nilGuard = new StringBuilder(); | ||
StringBuilder outputPath = new StringBuilder("result"); | ||
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List<MemberShape> outputMemberPath = paginationInfo.getOutputTokenPath(); | ||
for (int i = 0; i < outputMemberPath.size(); i++) { | ||
MemberShape memberShape = outputMemberPath.get(i); | ||
outputPath.append("."); | ||
outputPath.append(symbolProvider.toMemberName(memberShape)); | ||
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// Don't need to check the last member here as we won't dereference it | ||
if (i != outputMemberPath.size() - 1) { | ||
if (i != 0) { | ||
nilGuard.append(" && "); | ||
} | ||
nilGuard.append(outputPath); | ||
nilGuard.append(" != nil"); | ||
} | ||
} | ||
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Runnable setToken = () -> { | ||
writer.write("p.nextToken = $L", outputPath); | ||
}; | ||
if (nilGuard.length() > 0) { | ||
writer.openBlock("if $L {", "}", nilGuard.toString(), setToken::run); | ||
} else { | ||
setToken.run(); | ||
} | ||
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writer.openBlock("if p.options.StopOnDuplicateToken && " | ||
+ "params.$L != nil && p.nextToken != nil && " | ||
+ "*params.$L == *p.nextToken {", "", inputMember, inputMember, () -> { | ||
writer.write("p.done = false"); | ||
writer.openBlock("} else {", "}", () -> writer.write("p.done = true")); | ||
}); | ||
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writer.write(""); | ||
writer.write("return result, nil"); | ||
}); | ||
} | ||
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private void writePaginatorOptions( | ||
Model model, | ||
SymbolProvider symbolProvider, | ||
GoWriter writer, | ||
Symbol operationSymbol, | ||
Optional<MemberShape> pageSizeMember, | ||
Symbol optionsSymbol | ||
) { | ||
writer.writeDocs(String.format("%s is the paginator options for %s", optionsSymbol.getName(), | ||
operationSymbol.getName())); | ||
writer.openBlock("type $T struct {", "}", optionsSymbol, () -> { | ||
pageSizeMember.ifPresent(memberShape -> { | ||
MemberShape limitShape = pageSizeMember.get(); | ||
limitShape.getMemberTrait(model, DocumentationTrait.class).ifPresent(documentationTrait -> { | ||
writer.writeDocs(documentationTrait.getValue()); | ||
}); | ||
writer.write("Limit $P", symbolProvider.toSymbol(limitShape)); | ||
writer.write(""); | ||
}); | ||
writer.writeDocs("Set to true if pagination should stop if the service returns " | ||
+ "the same taken passed to it"); | ||
writer.write("StopOnDuplicateToken bool"); | ||
}); | ||
writer.write(""); | ||
} | ||
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private void writeClientOperationInterface( | ||
GoWriter writer, | ||
Symbol operationSymbol, | ||
Symbol inputSymbol, | ||
Symbol outputSymbol, | ||
Symbol interfaceSymbol | ||
) { | ||
Symbol contextSymbol = SymbolUtils.createValueSymbolBuilder("Context", SmithyGoDependency.CONTEXT) | ||
.build(); | ||
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writer.writeDocs(String.format("%s is a client that implements the %s operation.", | ||
interfaceSymbol.getName(), operationSymbol.getName())); | ||
writer.openBlock("type $T interface {", "}", interfaceSymbol, () -> { | ||
writer.write("$L($T, $P, ...func(*Options)) ($P, error)", operationSymbol.getName(), contextSymbol, | ||
inputSymbol, outputSymbol); | ||
}); | ||
writer.write(""); | ||
writer.write("var _ $T = (*Client)(nil)", interfaceSymbol); | ||
writer.write(""); | ||
} | ||
} |
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