Syntactic analysis is one of the stages of checking whether the data conforms to the correct syntax of a programming language. It is performed by analyzing the syntactic structure. This process may seem complicated until you understand its basis. This is what we will help you do.
Why do I need a parser?
Before learning new processes, you should understand why you need them. This type of analysis helps to solve at least four problems:
- Checking the grammatical component of the code.
- Providing help in adapting the code to the applied rules.
- Checking open brackets for closing balance.
- Determining the existence of each ad type.
It is a reliable assistant that allows you to verify the correctness of the input data.
Basic concepts and terms
Syntactic data analysis works in multitasking mode, and not surprisingly, it has a lot of terms and concepts that may be new. We’ve selected a few that are most commonly encountered.
A sentence is characters in the same alphabet combined into a group.
A lexeme is the lowest level unit of language of synthetic origin.
Markers are a category of lexemes.
A reserved word is a word that is not available for use as a name. Also, the keyword (second name) cannot be used as a variable identifier.
Noise words are additional words that improve readability.
Comments – a part of the document highlighted with /* */ or //Blank.
Separators are a syntactic element that marks the end and beginning of a unit.
Identifiers are a length restriction to improve readability.
You can find a complete data analyzer dictionary to learn all terms and concepts. However, we advise you to do it gradually, memorizing all the basics in practice.
Components of syntactic analysis
Like mobile proxies, syntactic parsing has different components and formats. Numeric data formats, as well as date and time formats, are worth highlighting separately.
Numeric data formats
The numeric data format analyzes data represented by numbers and special characters. In essence, these are integer data types – DT_I1, DT_UI1, DT_I2, DT_UI2 DT_I4, DT_UI4, DT_I8 and DT_UI8. In this section, there are data that are supported by the analysis system and data that are not supported.
| Quick Digital Analysis supports the following data: | Quick Digital Analysis does NOT support the following data: |
| Values in which tablatures are treated as zeros, e.g. “123”. | It is impossible to analyze a value that includes the monetary symbols of any country. |
| If the value is preceded by a plus sign, minus sign, or no sign at all. For example: +123, -123 or 123 | Blank space, carriage return, and line feed characters are not possible. |
| The use of Arabic numerals in quantities of one or more. | Exponential representation of numbers. For example, analyzing the number 1E+10 is impossible. |
It’s also worth remembering a few output rules. In particular:
- For positive numbers, no sign is used.
- For negative numbers, the sign “-” is used before the number itself.
- There are no spaces between characters.
- Arabic numerals from 0 to 9 are used.
It is critical to enter the data by following all the rules. Otherwise, the analysis will not be performed, or will be performed incorrectly.
Date and time formats
In addition to numbers, quick analysis supports different date and time formats. They are worth considering separately, because, like SIM hosting, analysis in date and time formats has its own nuances.
1. Date data type
This type implies entering a date in the format to be analyzed. The syntax data analyzer supports the following string formats. When entering a date, the first character is allowed to be a space. For example, the format “ 06- 05- 2023” is acceptable. You can also explore other formats that are supported by the analyzer. We would like to tell you more about the formats that the analyzer does not support.
- You should enter the month value only in numeric format. Alphabetic signatures are not suitable. Correct – 06-05-2023, NOT correct – 06-May-2023.
- Truncated formats YYYYYYDDD and YYYYY-DDD.
- Ambiguous date formats.
- Dates described by a four-digit year, a two-digit week number of the year, and a one-digit day of the week number. For example, it is not acceptable to enter a date in the format YYYYYYNNNND and YYYYYY-NNN-D.
If you are just beginning your journey in analysis, choose the date formats that you are most comfortable with.
2. Data type “time”
To enter time data, you should use the following valid formats:
- Classic time format in 24-hour mode with an initial space. Example – “ 11:39”.
- Only the 24 hour format can be used.
- To make the analyzed data take into account the time zone format, it is necessary to provide it with the type DT_DBTIMESTAMPOFFSET. There are also additional conditions. For example, no space is included in the string. You can use HH:MM:SS[+HF:MM] to append the string with the time zone format.
There are quite a few rules for entering data in time and date format. However, it is worth mastering them, and all the laws of analysis will fall into place.
Data parsing process
In the parsing process, plain text is converted into a data tree. It shows the structure of the input sequences. This format is ideal for further transformation and processing. The data after processing can be represented as a dependency tree or as a constituent tree. Sometimes both presented variants are used.
Stages of syntactic analysis
After the process is started, lexical analysis takes place, which entails the compiler design process. The syntax tree is developed with the help of a particular language and its grammar. In addition, the program is checked to see if it conforms to the rules of the context free grammar. If the data is entered correctly, the program produces a tree. Otherwise, the result of the analysis is an error, which will change to a tree only after all inaccuracies are corrected.
Tools and techniques
In essence, a parser is a set of tools and technologies that allow you to analyze a large set of data and provide the result in the form of a structured system. Among the tools used are:
- ANTLR – parser generator
- Bison – parser generator
- Coco/R – scanner and parser generator
- GOLD – parser
- JavaCC – parser generator for Java language
- Lemon Parser – parser generator
- Lex – scanner generator
- Ragel – embedded parser generator
- Spirit Parser Framework – parser generator
- SYNTAX
- Syntax Definition Formalism
- UltraGram
- VivaCore
- Yacc – parser generator
This is not an exhaustive list. Analyzers can use other products to achieve results. You can check out the full list, and learn more about each technology by staying with us.
Types of algorithms
Syntactic analysis is performed using two types of algorithms – standard and fast. They differ not only in processing speed, but also in the amount of output data.
Fast Parse
Fast parse is a set of simple operational analysis actions. During the procedure, only local data types, dates and times are supported. The system does not use data conversion. By supporting the organic format of numeric types, the analyzer can provide only simple parsing procedures.
Standard Parse
The standard system, in turn, presents a larger scope of operations. It supports all data types that the conversion interface provides. This includes API data in the Oleaut32.dll and Ole2dsip.dll libraries.
Standard Analysis supports international data types, including those that are not subject to Fast Parse analysis. This gives more freedom, as well as a full nation of analysis data, which is easier to manipulate and apply for further processing.
Error recovery
When an error is detected, the analyzer must be able to report the error, handle the error, and continue with the analysis. Some of the most common errors include:
- Incorrect format for entering a name identifier.
- Missing semicolon, or unbalanced parenthesis. Such errors belong to the syntactic errors class. They are often made by users, especially when entering a large amount of data.
- Semantic error, which means incompatible values.
- Unreachable code and other errors of the logical group.
Errors may be detected at various stages of compilation. To fix them, the analyzer can use different systems, just like the proxy checker online. We will familiarize you with the three most common ones.
Panic mode recovery
This recovery method involves rejecting all input symbols. This occurs until a single assigned group is formed. At the moment when an error is detected, the analyzer ignores the input data with an error until we enter a delimiter. The uncomplicated method of emergency error recovery helps in detecting simple inaccuracies.
Phrase-level recovery
To continue analysis from where the compiler left off, it corrects the program by deleting or inserting tokens. This allows it to make corrections to the signal that remains, replace the prefix, and continue the parsing process.
Error Productions
Error production involves expanding the grammar of the language that is the source of the error. After that, the parser performs error diagnosis of the construct and provokes its correction.
Examples of using syntactic analysis
Let’s take a little rest now and consider the principle of syntactic analysis with an example that will clearly demonstrate what syntactic analysis is. Syntax is a language of communication between a human and a computer. For example, you have set a task to make the computer cook your favorite dish, let it be borscht. To do this, you need to write the right query.
The correct syntax would look like this: print(“Let’s cook borscht.”). The incorrect one is prin(“Let’s cook borscht.”). As you realize, there can be many incorrect variants. One error and you have already created an incorrect query. The analyzer helps you calculate these errors, detect and correct them. It helps you to find a common language with the computer and make it “cook” a tasty borscht after all.
Disadvantages of using parsers
Analyzers have a number of disadvantages. This applies even to modern systems. Hopefully, analyzers will soon get a new impetus in development so that these disadvantages will come to naught. So:
- By performing semantic analysis, the system is unable to determine the validity of a token.
- Until the token is used, it is impossible to decide whether it is used or initialized.
- The analyzer is not able to determine whether an action is performed or not.
It is also worth mentioning the difficulty in mastering. Despite the simple interface and functionality, analyzers require certain skills. This applies to all the stages of use, from entering data to reading the results.
Let’s summarize
Considering a complex topic today, we have touched upon many important nuances. Bringing our conversation to its logical conclusion, everything said is worth systematizing and summarizing a number of results. We will highlight the 10 most important points that are worth remembering.
Parsing is the second stage of the compiler development process. The first stage is lexical analysis.
Among the important terms and concepts, you need to memorize the basic ones – lexeme, comments, reserved words, keywords, noise words. More useful vocabulary can be found in the article.
The job of the analyzer is to check the format of the input data, reject and offer solutions to data in the wrong format.
The analyzer helps to adapt existing rules to code writing.
The rules that convert the initial character to a string determine the grammatical origin.
A CFG is a left-recursive grammar that has at least one product.
During analysis, lexical, syntactic, and semantic errors occur. This list may include other, less common errors.
By enclosing the brackets element in a square, you can specify the sleep symbol.
The analysis can be standard and quick.
The main disadvantage of the parser method is that it is impossible to determine whether the token is valid or not.
Hopefully we have been able to answer your questions regarding syntactic analysis and open the door to understanding a complex topic. You will find more interesting and practical material on the site. You can also find out what the price of LTESocks proxies is, how to use the system for your own protection, and whether it is worthwhile to connect proxies for ordinary users.
