131 lines
3.4 KiB
Markdown
131 lines
3.4 KiB
Markdown
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JSON representation
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===================
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Nodes (and comments) implement the `JsonSerializable` interface. As such, it is possible to JSON
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encode the AST directly using `json_encode()`:
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```php
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<?php
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use PhpParser\ParserFactory;
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$code = <<<'CODE'
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<?php
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/** @param string $msg */
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function printLine($msg) {
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echo $msg, "\n";
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}
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CODE;
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$parser = (new ParserFactory)->create(ParserFactory::PREFER_PHP7);
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try {
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$stmts = $parser->parse($code);
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echo json_encode($stmts, JSON_PRETTY_PRINT), "\n";
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} catch (PhpParser\Error $e) {
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echo 'Parse Error: ', $e->getMessage();
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}
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```
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This will result in the following output (which includes attributes):
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```json
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[
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{
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"nodeType": "Stmt_Function",
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"byRef": false,
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"name": {
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"nodeType": "Identifier",
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"name": "printLine",
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"attributes": {
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"startLine": 4,
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"endLine": 4
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}
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},
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"params": [
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{
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"nodeType": "Param",
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"type": null,
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"byRef": false,
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"variadic": false,
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"var": {
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"nodeType": "Expr_Variable",
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"name": "msg",
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"attributes": {
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"startLine": 4,
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"endLine": 4
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}
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},
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"default": null,
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"attributes": {
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"startLine": 4,
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"endLine": 4
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}
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}
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],
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"returnType": null,
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"stmts": [
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{
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"nodeType": "Stmt_Echo",
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"exprs": [
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{
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"nodeType": "Expr_Variable",
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"name": "msg",
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"attributes": {
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"startLine": 5,
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"endLine": 5
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}
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},
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{
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"nodeType": "Scalar_String",
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"value": "\n",
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"attributes": {
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"startLine": 5,
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"endLine": 5,
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"kind": 2
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}
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}
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],
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"attributes": {
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"startLine": 5,
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"endLine": 5
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}
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}
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],
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"attributes": {
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"startLine": 4,
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"comments": [
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{
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"nodeType": "Comment_Doc",
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"text": "\/** @param string $msg *\/",
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"line": 3,
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"filePos": 9,
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"tokenPos": 2
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}
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],
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"endLine": 6
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}
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}
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]
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```
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The JSON representation may be converted back into an AST using the `JsonDecoder`:
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```php
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<?php
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$nodeDecoder = new PhpParser\NodeDecoder();
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$ast = $nodeDecoder->decode($json);
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```
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Note that not all ASTs can be represented using JSON. In particular:
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* JSON only supports UTF-8 strings.
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* JSON does not support non-finite floating-point numbers. This can occur if the original source
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code contains non-representable floating-pointing literals such as `1e1000`.
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If the node tree is not representable in JSON, the initial `json_encode()` call will fail.
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From the command line, a JSON dump can be obtained using `vendor/bin/php-parse -j file.php`.
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