BrychanD/159.341_Assignment_1
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Condensed some code.

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Improved docstrings where possible
This commit is contained in:
Brychan Dempsey 2021-03-17 17:11:18 +13:00
parent c7858791f4
commit 087d8d0754
1 changed files with 22 additions and 34 deletions
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56
Assignment 1/Program.cs
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@ -11,6 +11,9 @@ namespace Assignment_1
{
class Program
{
/// <summary>
/// Flags to set object properties.
/// </summary>
[Flags]
enum VariableFlags
{
@ -21,23 +24,17 @@ namespace Assignment_1
Undef = 8
}
/// <summary>
/// This captures the end-point of each part of an expression (in the stream), to validate the syntax
/// Optionally also captures the parsed string for each expression.
///
/// For this program, a word is considered to be any non-whitespace value bounded by whitespace or the array boundary.
///
/// </summary>
static Dictionary<string, Tuple<string, VariableFlags>> Symbols = new Dictionary<string, Tuple<string, VariableFlags>>
{
static Dictionary<string, Tuple<string, VariableFlags>> Symbols = new()
{
{ "SPACE", new Tuple<string, VariableFlags>(" ", VariableFlags.Reserved | VariableFlags.NoPrint) },
{ "TAB", new Tuple<string, VariableFlags>("\t", VariableFlags.Reserved | VariableFlags.NoPrint) },
{ "NEWLINE", new Tuple<string, VariableFlags>("\n", VariableFlags.Reserved | VariableFlags.NoPrint) },
{ "CARRIAGE_RETURN", new Tuple<string, VariableFlags>("\r", VariableFlags.Reserved | VariableFlags.NoPrint) }
};
static List<char> ForbiddenChars = new List<char>
/// <summary>
/// Characters that cannot appear in a normal string
/// </summary>
static readonly List<char> ForbiddenChars = new()
{
'$', '\\', '\"', '\''
};
@ -100,18 +97,15 @@ namespace Assignment_1
long pos = source.Position;
source.Write(Encoding.UTF8.GetBytes(s));
source.Position = pos;
int g = 0;
}
// parse the statement or list of statements;
// This is done by reading the next word
SkipWhitespace(source);
long initPos = source.Position;
long position = FindNextWord(source, out string word);
object statementType;
try
{
if (Enum.TryParse(typeof(statements), word, out statementType))
if (Enum.TryParse(typeof(statements), word, out object statementType))
{
// By turning the result of the command into an action,
// we can defer processing the final result until the end of this control flow
@ -183,7 +177,7 @@ namespace Assignment_1
{
throw new ParserException("expected a semi-colon", 0, source.Position);
}
}
else
{
@ -439,26 +433,17 @@ namespace Assignment_1
/// <returns></returns>
long FindExpression(Stream s, out string expression)
{
// Expressions are one or more occurances of a variable name or literal definition.
// To make logical sense, there needs to be an operator between them. Typically, for strings, this is
// the append operator: +
// Variable symbols should be evaluated immediately.
// Start by ensuring we don't try reading past the end of the stream
// Also check for the EoS
long realStart = s.Position;
string result = "";
// iterate through values until we reach either the end of the stream or the end-of-statement
while (s.Position < s.Length && !IsNextEoS(s))
{
long currStart = s.Position;
if (IsNextEoS(s, '+'))
{
s.Position = FindNextWord(s, out _);
}
else
{
string value;
long firstPos = s.Position;
long val = FindValue(s, out value);
long val = FindValue(s, out string value);
if (val == -1)
{
Console.WriteLine("Could not parse value");
@ -506,8 +491,7 @@ namespace Assignment_1
}
else
{
string keyValue;
long t = FindExistingIdentifier(s, out keyValue);
long t = FindExistingIdentifier(s, out string keyValue);
// Set the key value to result + this read string
//keyValue = result + keyValue;
@ -528,8 +512,7 @@ namespace Assignment_1
}
long FindExistingIdentifier(Stream s, out string returnedKey)
{
string identifier;
long wordEnd = FindNextWord(s, out identifier);
long wordEnd = FindNextWord(s, out string identifier);
if (identifier.Length > 1 && identifier.EndsWith(';'))
{
// Remove the trailing semicolon from the parse & backtrack the identifier length one spot
@ -608,10 +591,15 @@ namespace Assignment_1
/// <returns></returns>
static long FindNextWord(Stream s, out string nextWord)
{
StringBuilder newWord = new StringBuilder();
StringBuilder newWord = new();
// Record our current position
long start = s.Position;
// Check if the character at the current pos is whitespace, if so, keep advancing until it isn't
// Check if the character at the current pos is whitespace, if so, keep advancing until it isn't.
// NB: Whitespace includes carriage returns or line feeds,
// so 'set\r\n
// var
// "expression";
// should be valid
char currentChar = ReadChar(s);
while (s.Position < s.Length && char.IsWhiteSpace(currentChar))
{