Parse code into operation triads IR

Q: Parse code into operation triads IR

This question evaluates parsing and IR-generation skills, including tokenization, AST or three-address (operation triads) construction, deterministic control-flow serialization, and management of temporaries and labels.

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This is a medium difficulty Coding & Algorithms question, commonly asked during Onsite rounds at Mithril.

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This question is commonly asked for Software Engineer candidates at Mithril during technical interviews.

Question

Problem: Operation-Triads Parsing (Mini Language)

You are given a small, line-based programming language consisting of assignment statements and non-nested if–else blocks. Your task is to parse the input program and deserialize it into a deterministic intermediate representation (IR).

You may output either:

a flat list of operation triads (three-address/triad form), or
an equivalent structured representation (e.g., AST/JSON).

Language

1) Statements

Assignment (one per line)
- Examples:
  - a = 1
  - x = b + c

If–Else (block form)

if (condition) {
  assignment
} else {
  assignment
}

2) Expressions

Operands: variable identifiers ( a , b , x ) or integers ( 1 , 2 , 10 )
Binary operators: + , - , * , /
Conditions use comparison operators (at least == ), e.g. a + b == 3
The condition is a binary comparison between two expressions.

3) Control-flow constraints

if–else blocks cannot be nested .
Every if must have an else .
Each { ... } block contains exactly one assignment statement .

Input

A list/array of strings, each string is one line of code, in order.

Example input:

[a = 1,
 if (a + b == 3) {
 x = 10
 } else {
 x = 20
 }
]

Output

Produce an IR that preserves execution order and control flow.

If using operation triads, each instruction is a tuple:

(op, arg1, arg2)

You may introduce temporary values t1, t2, … and labels L1, L2, … as needed.

Example (one acceptable triad-style output for the sample):

(=, 1, a)
(+, a, b)        -> t1
(==, t1, 3)      -> t2
(if_false, t2, L1)
(=, 10, x)
(goto, L2, _)
(label, L1, _)
(=, 20, x)
(label, L2, _)

Requirements

Tokenize and parse the input lines.
Enforce the stated constraints (non-nested if , must have else , exactly one assignment per block).
Output must be deterministic and serializable.
Clearly define how temporaries and labels are generated.