Class ELParser

java.lang.Object
io.micronaut.el.parser.ELParser
public final class ELParser extends Object
The parser of the Jakarta Expression Language grammar collected in the section 1.26 of the specification.

The parser is a recursive descent implementation of the grammar, with the operator precedence described in the section 1.16 of the specification.

Since:
1.0
Author:
Denis Stepanov

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final int
    DEFAULT_MAX_DEPTH
    The nesting depth an expression may reach by default.

  • Method Summary

    Modifier and Type
    Method
    Description
    static ELNode
    parse(String expression)
    Parses an expression, which can be a literal-expression, an eval-expression or a composite expression, nested at most DEFAULT_MAX_DEPTH levels deep.
    static ELNode
    parse(String expression, int maxDepth)
    Parses an expression, which can be a literal-expression, an eval-expression or a composite expression.
    static ELNode
    parseEval(String expression)
    Parses an expression that must consist of a single eval-expression, as required for a method expression by the section 1.2.3 of the specification.
    static ELNode
    parseEval(String expression, int maxDepth)
    Parses an expression that must consist of a single eval-expression, as required for a method expression by the section 1.2.3 of the specification.

    Methods inherited from class Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • DEFAULT_MAX_DEPTH

      public static final int DEFAULT_MAX_DEPTH
      The nesting depth an expression may reach by default.

      The parser is a recursive descent implementation and the tree it produces is walked recursively by every consumer, so an expression nested beyond the depth of the call stack would fail with a StackOverflowError rather than with an exception of the specification. An expression string built at runtime therefore has to be bounded, and no expression a person writes comes close to this limit.

      A parenthesised sub-expression is the level that costs the most stack, around fifteen frames of the recursive descent, so this default holds on a thread whose stack is half of the usual one. Parse with parse(String, int) to raise it for expressions generated by a tool.

      See Also:

  • Method Details

    • parse

      public static ELNode parse(String expression)
      Parses an expression, which can be a literal-expression, an eval-expression or a composite expression, nested at most DEFAULT_MAX_DEPTH levels deep.
      Parameters:
      expression - The expression
      Returns:
      The parsed expression

    • parse

      public static ELNode parse(String expression, int maxDepth)
      Parses an expression, which can be a literal-expression, an eval-expression or a composite expression.
      Parameters:
      expression - The expression
      maxDepth - The nesting depth the expression may reach, beyond which it is rejected
      Returns:
      The parsed expression

    • parseEval

      public static ELNode parseEval(String expression)
      Parses an expression that must consist of a single eval-expression, as required for a method expression by the section 1.2.3 of the specification.
      Parameters:
      expression - The expression
      Returns:
      The parsed expression

    • parseEval

      public static ELNode parseEval(String expression, int maxDepth)
      Parses an expression that must consist of a single eval-expression, as required for a method expression by the section 1.2.3 of the specification.
      Parameters:
      expression - The expression
      maxDepth - The nesting depth the expression may reach, beyond which it is rejected
      Returns:
      The parsed expression