SimpleParser (Smithy API 1.21.0)

java.lang.Object
- software.amazon.smithy.utils.SimpleParser

```
public class SimpleParser
extends java.lang.Object
```
A simple expression parser that can be extended to implement parsers for small domain specific languages.
This parser consumes characters of an in-memory string while tracking the current 0-based position, 1-based line, and 1-based column. Expectations can be made on the parser to require specific characters, and when those expectations are not met, a syntax exception is thrown.

Constructor Summary

Constructors
Constructor and Description
`SimpleParser(java.lang.String expression)` Creates a new SimpleParser and sets the expression to parse.
`SimpleParser(java.lang.String expression, int maxNestingLevel)` Creates a new SimpleParser and sets the expression to parse.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`br()` Skips spaces then expects that the next character is either the end of the expression or a line break (\n, \r\n, or \r).
`int`	`column()` Gets the current 1-based column number of the parser.
`void`	`consumeRemainingCharactersOnLine()` Skips over the remaining characters on a line but does not consume the newline character (\n or \r\n).
`int`	`consumeUntilNoLongerMatches(java.util.function.Predicate<java.lang.Character> predicate)` Reads a lexeme from the expression while the given `predicate` matches each peeked character.
`void`	`decreaseNestingLevel()` Decreases the current nesting level of the parser.
`boolean`	`eof()` Checks if the parser has reached the end of the expression.
`char`	`expect(char... tokens)` Expects that the next character is one of a fixed set of possible characters.
`char`	`expect(char token)` Expects that the next character is the given character and consumes it.
`java.lang.String`	`expression()` Gets the expression being parsed.
`void`	`increaseNestingLevel()` Increases the current nesting level of the parser.
`int`	`line()` Gets the current 1-based line number of the parser.
`int`	`nestingLevel()` Gets the current 0-based nesting level of the parser.
`char`	`peek()` Returns the current character of the expression, but does not consume it.
`char`	`peek(int offset)` Returns the current character of the expression + `offset` characters, but does not consume it.
`java.lang.String`	`peekSingleCharForMessage()` Peeks the next character and returns [EOF] if the next character is past the end of the expression.
`int`	`position()` Gets the current 0-based position of the parser.
`void`	`skip()` Skips a single character while tracking lines and columns.
`java.lang.String`	`sliceFrom(int start)` Gets a slice of the expression starting from the given 0-based character position, read all the way through to the current position of the parser.
`void`	`sp()` Skip 0 or more spaces (that is, ' ' and '\t').
`java.lang.RuntimeException`	`syntax(java.lang.String message)` Creates a syntax error that adds some context to the given message.
`void`	`ws()` Skip 0 or more whitespace characters (that is, ' ', '\t', '\r', and '\n').

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - SimpleParser
```
public SimpleParser(java.lang.String expression)
```
    Creates a new SimpleParser and sets the expression to parse.
    
    Parameters:
    
    expression - Expression to parser.
  - SimpleParser
```
public SimpleParser(java.lang.String expression,
                    int maxNestingLevel)
```
    Creates a new SimpleParser and sets the expression to parse.
    By default, no maximum parsing level is enforced. Setting the maxParsingLevel to 0 disables the enforcement of a maximum parsing level.
    
    Parameters:
    
    expression - Expression to parse that must not be null.
    
    maxNestingLevel - The maximum allowed nesting level of the parser.
- Method Detail
  - expression
```
public final java.lang.String expression()
```
    Gets the expression being parsed.
    
    Returns:
    
    Returns the expression being parsed.
  - position
```
public final int position()
```
    Gets the current 0-based position of the parser.
    
    Returns:
    
    Returns the parser character position.
  - line
```
public final int line()
```
    Gets the current 1-based line number of the parser.
    
    Returns:
    
    Returns the current line number.
  - column
```
public final int column()
```
    Gets the current 1-based column number of the parser.
    
    Returns:
    
    Returns the current column number.
  - eof
```
public final boolean eof()
```
    Checks if the parser has reached the end of the expression.
    
    Returns:
    
    Returns true if the parser has reached the end.
  - peek
```
public final char peek()
```
    Returns the current character of the expression, but does not consume it.
    
    Returns:
    
    Returns the peeked character.
  - peek
```
public final char peek(int offset)
```
    Returns the current character of the expression + offset characters, but does not consume it.
    If the end of the expression is reached or if the peeked offset is calculated to be less than 0, Character.MIN_VALUE is returned (that is, '\0').
    
    Parameters:
    
    offset - The number of characters to peek ahead (positive or negative).
    
    Returns:
    
    Returns the peeked character.
  - expect
```
public final char expect(char token)
```
    Expects that the next character is the given character and consumes it.
    
    Parameters:
    
    token - The character to expect.
    
    Returns:
    
    Returns the expected character.
  - peekSingleCharForMessage
```
public final java.lang.String peekSingleCharForMessage()
```
    Peeks the next character and returns [EOF] if the next character is past the end of the expression.
    
    Returns:
    
    Returns the peeked next character.
  - expect
```
public final char expect(char... tokens)
```
    Expects that the next character is one of a fixed set of possible characters.
    
    Parameters:
    
    tokens - Characters to expect.
    
    Returns:
    
    Returns the consumed character.
  - syntax
```
public java.lang.RuntimeException syntax(java.lang.String message)
```
    Creates a syntax error that adds some context to the given message.
    
    Parameters:
    
    message - Message for why the error occurred.
    
    Returns:
    
    Returns the created syntax error.
  - ws
```
public void ws()
```
    Skip 0 or more whitespace characters (that is, ' ', '\t', '\r', and '\n').
  - sp
```
public void sp()
```
    Skip 0 or more spaces (that is, ' ' and '\t').
  - br
```
public void br()
```
    Skips spaces then expects that the next character is either the end of the expression or a line break (\n, \r\n, or \r).
    
    Throws:
    
    java.lang.RuntimeException - if the next non-space character is not EOF or a line break.
  - skip
```
public void skip()
```
    Skips a single character while tracking lines and columns.
  - consumeRemainingCharactersOnLine
```
public void consumeRemainingCharactersOnLine()
```
    Skips over the remaining characters on a line but does not consume the newline character (\n or \r\n).
    This method will also terminate when the end of the expression is encountered.
    This method is useful, for example, for skipping the text of a commented out line in an expression. If the contents of the skipped line are required, then store the current position before invoking this method using position(), then call this method, then get the contents of the skipped characters using sliceFrom(int).
  - sliceFrom
```
public final java.lang.String sliceFrom(int start)
```
    Gets a slice of the expression starting from the given 0-based character position, read all the way through to the current position of the parser.
    
    Parameters:
    
    start - Position to slice from, ending at the current position.
    
    Returns:
    
    Returns the slice of the expression from start to position.
  - consumeUntilNoLongerMatches
```
public final int consumeUntilNoLongerMatches(java.util.function.Predicate<java.lang.Character> predicate)
```
    Reads a lexeme from the expression while the given predicate matches each peeked character.
    
    Parameters:
    
    predicate - Predicate that filters characters.
    
    Returns:
    
    Returns the consumed lexeme (or an empty string on no matches).
  - increaseNestingLevel
```
public final void increaseNestingLevel()
```
    Increases the current nesting level of the parser.
    This method can be manually invoked when parsing in order to prevent parsing too deeply using recursive descent parsers.
    
    Throws:
    
    java.lang.RuntimeException - if the nesting level is deeper than the max allowed nesting.
  - decreaseNestingLevel
```
public final void decreaseNestingLevel()
```
    Decreases the current nesting level of the parser.
  - nestingLevel
```
public int nestingLevel()
```
    Gets the current 0-based nesting level of the parser.
    
    Returns:
    
    Returns the current nesting level.

Class SimpleParser

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

SimpleParser

SimpleParser

Method Detail

expression

position

line

column

eof

peek

peek

expect

peekSingleCharForMessage

expect

syntax

ws

sp

br

skip

consumeRemainingCharactersOnLine

sliceFrom

consumeUntilNoLongerMatches

increaseNestingLevel

decreaseNestingLevel

nestingLevel